Paying for a college education is a tough nut to crack for parents, but with the right opportunities, you can do it -- if you have a long enough investment horizon.

We asked three Motley Fool contributors to identify a stock they believe will give investors looking to pay for their child's college education the right mix of growth and returns, so read on to find out why Cronos Group (NASDAQ:CRON), Cisco Systems (NASDAQ:CSCO), and Walmart (NYSE:WMT) are perfect stocks for that investment goal.

Piggy bank with a college graduation cap on

Image source: Getty Images.

A big opportunity for patient investors 

George Budwell (Cronos Group): The legal marijuana industry is projected to blossom into no less than a $50 billion space by the end of the next decade, and this figure could rise to as much as $200 billion if cannabis can effectively disrupt ancillary markets like pharmaceuticals, cosmetics, and consumer goods. The bulk of this monstrous growth, though, isn't expected to materialize until the latter half of the 2020s, thanks to a variety of legal and logistical barriers. Put simply, marijuana stocks should be viewed mainly as long-term investing vehicles at this extremely early stage of the game. 

Which pot stock has the best chance at generating sizable returns for patient investors? Canada's Cronos Group has a substantial leg up on the competition by virtue of its $1.8 billion tie-up with Marlboro maker Altria (NYSE:MO). This enormous partnering agreement instantly gave Cronos the cash necessary to wait out the industry's ongoing growing pains and to freely explore out-of-the box ideas such as the production of cannabinoids via fermentation.

At present, Cronos is in the process of building upon its collaboration with Ginkgo Bioworks to produce a wide variety of cannabinoids using genetically modified yeast -- as evinced by its recent acquisition of a fermentation and manufacturing facility from Apotex Fermentation last month. Cronos and Altria in turn could end up with a one-of-a-kind production platform to supply their novel vape product line. No other major cannabis company can make this claim right now. 

All told, Cronos' true value proposition remains a bit fuzzy at this point because the company has decided to branch out into more speculative areas of this emerging industry. But it does have the backing of a major Fortune 500 company with an amazing track record of creating value for its shareholders. That fact alone bodes exceedingly well for Cronos' long-term prospects.     

Facilitating the connectivity revolution 

Keith Noonan (Cisco Systems): Cisco has long enjoyed a dominant position in the router and switch hardware markets, providing key networking devices that have helped power the information technology revolution over the last three decades. Continued dominance in network hardware continues to define the business, and gives it a great foundation and launching pad, but Cisco isn't standing still.

Cisco's sustained dominance in networking hardware allowed the company to build up a massive cash pile, and that advantage is helping the company reposition to ensure that it's at the forefront of connectivity. While its router and switch business will likely face long-term pressures due to increased competition and software taking over roles that previously required actual devices, the company is putting its assets to use in order to build what looks like a dominant position in the next generation of networking technology and services. Cisco is spending billions of dollars a year on acquisitions to bolster its strength in big trends including the Internet of Things, 5G, low-power wide-area networks, and a range of new security and data management technologies that will be needed to facilitate rapid growth in the number of connected devices and overall data load.

Cisco is also a great dividend stock. Even after rallying more than 90% over the last three years, shares yield roughly 2.4% at today's prices and are trading at a reasonable 19 times expected earnings. The big rally has much to do with its success in transitioning to a model that's heavier on software services and generates dependable recurring revenue, and it seems the positive impacts of this transformation will continue making themselves evident for years to come. 

A stalwart of growth and opportunity

Rich Duprey (Walmart): When investing for your child's college education, you want a stock that is reliable and stable, preferably one that pays a dividend to juice your returns, and one that will still be in business when it's time to cash in. Walmart (NYSE:WMT) gives you all those things and more.

The retailer has overcome the retail slump by figuring out that its bricks-and-mortar stores are its greatest asset in a world increasingly moving online. Not only do they serve their primary purpose of giving consumers a place to shop to find great value on groceries and other merchandise, but they can leverage their footprint by being distribution centers for online orders as well as pickup points for customers who can't or don't want to have their orders shipped to their homes.

Walmart is not only the largest retailer in the country, it is also the second-largest online store behind Amazon (NASDAQ:AMZN), and it has the potential to pad its lead as the largest online supermarket, as its rival largely remains unable to extend its e-commerce superiority to groceries.

While Walmart's stock is up 20% so far in 2019, it trades at a reasonable 22 times projected earnings but at just a fraction of its sales. Because it has been consolidating its e-commerce efforts and its physical assets to better align their operations for growth, it should be able to increase its sales above the competition's, which should also lead to its valuation catching up to its promise. 

With a dividend of $2.12 that currently yields about 2% annually, Walmart offers investors an opportunity to enhance their returns over time. And while any business can encounter trouble that causes it to crash, the likelihood is greater than not that Walmart will be here in 20 years in the future -- if not many more.