Aldehydes are more reactive than ketones because they have:

Explanation

The reactivity difference between aldehydes and ketones is mainly due to steric hindrance. In aldehydes, the carbonyl group is always at the end of the carbon chain, and there is an additional hydrogen atom attached to the carbonyl carbon. On the other hand, ketones have the carbonyl group in the middle of the carbon chain, with two carbon groups (alkyl or aryl groups) attached to the carbonyl carbon. The presence of these additional carbon groups in ketones leads to more steric hindrance compared to aldehydes. Steric hindrance makes it more difficult for nucleophiles to approach the electrophilic carbonyl carbon, thus reducing the reactivity of ketones compared to aldehydes. Therefore, option b is correct.