Select the correct direct form of the given sentence.

I asked my sister if she had returned the mobile phone to her friend.

I said to my sister, ‘Have you returned the mobile phone to your friend?’

The correct direct form of the given sentence is:

I said to my sister, "Have you returned the mobile phone to your friend?"

The other options are incorrect for the following reasons:

• I said to my sister, ‘did you return the mobile phone to my friend?’ - The past tense verb "did" is not appropriate in this context, as the speaker is asking about something that happened in the past and is still relevant in the present.
• I asked my sister, ‘have you return the mobile phone to my friend?’ - The verb "return" is missing the helping verb "to".
• I said to my sister, ‘have you returned the mobile phone to my friend?’ - The question mark is missing.