Palindromes are words, numbers, or sentences that read the same in forward or reverse order.
If we reverse TOO HOT TO HOOT, we get TOO HOT TO HOOT. It is the same when reversed.
If we reverse NEVER ODD OR EVEN, we get NEVER ODD OR EVEN. It is the same when reversed.
If we reverse STEP ON NO PETS, we get STEP ON NO PETS. It is the same when reversed.
If we reverse WHAT IT A DOG I SAW, we get WAS I, GOD, A TISAW. It is not the same when reversed.
Here, only option D is not read the same in forward or reverse order.
Hence, option D is correct.