Replace the underlined part with the correct option:

Had he worked hard for the tournament, he had aced the match.

Option D is the correct answer because it correctly conveys the conditional aspect of the situation described in the sentence.

In the original sentence, "Had he worked hard for the tournament, he had aced the match," the use of "had aced" is incorrect. The structure "had aced" is typically used for past perfect tense, indicating an action that was completed before another past action. However, in this context, the intent is to express a hypothetical or conditional scenario - if he had worked hard for the tournament, then he would have aced the match.

The correct construction for expressing this conditional scenario is "would have aced." The modal verb "would" indicates a hypothetical or conditional action in the past. So, "He would have aced" properly conveys the idea that if he had worked hard for the tournament, he would have aced the match.