Which one of the following is reduced with zinc and hydrochloric acid to give the corresponding hydrocarbon?

Reduction with zinc amalgam and concentrated $\text{HCl}$ is the Clemmensen reduction, which specifically reduces the carbonyl group ($C=O$) of aldehydes and ketones to a methylene group ($C{H}_2$).
Butan-2-one is a ketone; it will be reduced to n-butane. Esters, amides, and acids are not typically reduced to hydrocarbons under these conditions.