Correct Answer: I said to my brother, "Have you visited your friend who is in the hospital?"

Solution : The correct choice is the fourth option.

The steps of conversion are as follows:

• The reporting verb "asked" is changed to "said".
• The past perfect tense "had visited" is changed to the present perfect tense "have visited".
• The words of the speaker are enclosed in the inverted commas.
• The connector "if" is removed.
• "He" (third-person pronoun) is changed to "you" (second-person pronoun).

So, the correct sentence would be: I said to my brother, "Have you visited your friend who is in the hospital?"