Keeping in mind that Indirect objects work as a complement, and receive this name because the effect of the action of a verb doesn't flow directly to them. It is appropriate to state that the indirect object of the sentence is D. "friend". None of the other options could be because "milkshake" is the direct object of the sentence, "peacemaking" is an adjective that modifies the direct object of the sentence, and "Luis" is the subject of the sentence.