What will you do to save her?

Explanation

- The original sentence "What will you do to save her?" is in active voice, where the subject "you" performs the action of saving.- To convert it to passive voice, we need to make the action (saving) the subject, and the action is performed on it. Hence, the correct passive voice construction is "What will be done by you to save her?"- This construction emphasizes the action, rather than the person performing the action (you).