Please i am confused with this question. answer for me

Question

Which hydrocarbon has carbon Carbon double bond?

A. C4H6 B. C4H10 C. C5H12 D. C4H8

Answer 1

If no double bonds, then the number of H will be 2x the # of C + 2. So, B and C do not have double bonds.

If 1 double bond, then the number of H will be 2x the # of C. So, D would have a double bond.

A looks like a triple bond compound.