Wind/air.

The letter m

If answer A would be correct, then answer B ("Answer A or B") would also be correct. If answer B would be correct, then answer C ("Answer B or C") would also be correct. This leads to the conclusion that if either answer A or answer B would be the correct answer, there are at least two correct answers. This contradicts with the statement "there is only one correct answer to this question". If answer C would be correct, then there are no contradictions.

Therefore, the solution is answer C.

He was born on February 29.

wind

Because the batteries died.

36 (1+1) x (1+1) = 4 (2+2) x (2+2) = 16 (3+3) x (3+3) = 36

The fish bowl got knocked over. The bodies were goldfish.

Her legs.

Your right elbow

In military time. Both refer to 3:20

One of the coins is really not a nickel because nickel is the other coin.