The correct answer is C. He asked his servant why he was being so lazy that day.
The sentence “He said to his servant, ‘Why are you so lazy today?'” is in the present tense. This means that the speaker is asking about the servant’s laziness at that particular moment. Option A is incorrect because it uses the past tense (“had been”). Option B is incorrect because it uses the perfect tense (“has been”). Option D is incorrect because it uses the interrogative form (“was”).
The sentence “He asked his servant why he was being so lazy that day” is a direct question. This means that the speaker is asking the servant for a specific reason for his laziness. The other options are not direct questions.