The choices you've given here are a pretty scattered lot- 2 adult sized dual suspension mountain bikes, a boys' smaller mountain bike with 24" wheels, and a singlespeed cruiser. To help you, we need to know the kind of riding you do. Is it mostly in the city? On trails? Hilly? What's your budget?
Also, some information on your size and age would help. Unless you're pretty young, you won't want a bike with 24" wheels.
I and many others here would not recommend buying a dual suspension bike from Wal-Mart (or any other department store) due to poor quality components and, in some cases, questionable or even flat out incorrect assembly of the bike. If you have to buy from Wal-Mart, go as simple as possible in your bike choice- avoid suspension. If you can, I'd recommend going to a bike store to get help with choosing a bike and being fitted properly to it.