Correct Answer: The librarian asked her if she could return the books.

Solution : The correct choice is the first option .

In the conversion to indirect speech, we follow the steps as follows:

• In indirect speech, the reporting verb "said" is changed to "asked" because it's a question.
• The pronoun "you" is changed to "she" because the librarian is the one asking.
• The modal verb "can" changes to "could" to maintain the correct sequence of tenses. We need to transform the question into an indirect question format by using "if" or "whether".
• "If" is used to connect subordinate clauses in the case of yes or no questions.

Therefore, the correct answer is: The librarian asked her if she could return the books.