I have 2x2 ft, 3x3 ft,4x4 ft,and 5 x5 ft tile. Which can be used to cover a 12x12 ft. Floor

It's fun to drive teachers nuts by saying 'any of them,' which is true if you cut them.
Actually as you can see, 5 and 4 and 3 = 12, so there's one side covered.
You don't say how many of each tile you have.

I remember a story years ago of a bright kid who was asked the question 'which of these numbers is divisible by 5?' and he said 'all of them.' The test forgot to ask 'which of these numbers is EVENLY divisible.' Tests and teachers can be wrong.

About 2 years before my dad died I asked him to teach me physics. I had a textbook from an exclusive prep school. We started in and right from the start, my dad complained that some of the answers to questions at the end of each chapter were flat out wrong. So we bought Physics for Dummies - same thing! He wrote to the author, who said that the publisher changed problems on him without correcting answers! What the heck.

Actually you can use all of them without cutting, as long as you're allowed to mix them. For example you can tile a 12 x 12 room with a mix of 5x5's and 2x2's, or you can use a combinatoin of 4x4's, 3x3's and 2x2's. The question of whether you can use 2x2's, 3x3's or 4x4's exclusively is trivial.