A boy of 17 years marries a girl of 15 years. The marriage is-

n Hindu law, the marriage of a boy of 17 years and a girl of 15 years would generally be considered voidable. Voidable marriages are those that are valid when entered into but can be annulled by either party or their guardian due to certain legal impediments, such as the age of consent. However, until annulled by a competent court, the marriage remains legally binding.

Therefore, the correct answer is Option B: Voidable.