"Marc prefers cycling to driving" is correct. You could also say "Marc prefers cycling over driving," but you cannot use "than" in this case. I am not sure of the explanation other than this is just what we pair with the word "prefers" in English. If you use an adjective or another verb, "than" will usually be correct: "Marc likes cycling more than driving" (verb = like; notice that we also have to add "more" before "than" because the word "like" does not carry any element of comparison without adding "more," unlike the word "prefer," which inherently implies some sort of comparison) "Cycling is more fun than driving" (adjective = fun) "Cycling is better than driving" (adjective = better) I hope that helps!

Marc prefers cycling to driving. You could also say "Marc prefers cycling rather than driving."

The pattern for the verb "to prefer" is "prefer A to B". "Than" is used for comparatives, and I think Sarah has answered that part thoroughly. Also, remember that Marc = he, so you need "Marc prefers..." There's also a big difference between "true" and "correct" in English. True things exist in reality. Correct things are without any errors. Your question should be, "Which one is correct, to or than?" If you write "Marc prefers cycling to driving" and then ask "Is it true?", my answer is this: Find Marc and ask him!