Which response by a father indicates understanding of Y-linked inheritance?

The correct response indicating an understanding of Y-linked inheritance is the statement about passing on the condition to his baby. Y-linked inheritance involves genes located on the Y chromosome, which is only passed from father to son. Therefore, if a father has a condition that is Y-linked, he can only transmit it to his male offspring. This understanding is critical because it highlights that the condition can only be inherited if the offspring is male and directly related to the father.

The other responses demonstrate a misunderstanding of how genetic inheritance works. The statement about the baby inheriting the disease from the mother is inaccurate in the context of Y-linked conditions because only the Y chromosome from the father can transmit such traits. Mentioning a grand-aunt with the same condition implies that it could be passed down through female relatives, which is not characteristic of Y-linked inheritance. Finally, the notion of both parents passing a disease to the baby does not apply, as Y-linked inheritance specifically involves only the father’s contributions. Each of these misunderstandings reinforces why the selected response reflects a correct comprehension of Y-linked inheritance principles.