The correct answer is: A. I said to him, “You are not working hard.”
The other options are incorrect because they do not use the correct verb tense. The sentence “I told him that he was not working hard” is in the past tense, so the verb in the direct quote should also be in the past tense. Option B, “I told to him, ‘You are not working hard,'” uses the present tense verb “told,” which is incorrect. Option C, “I said, ‘You are not working hard,'” is also incorrect because it does not use the direct object pronoun “him.” Option D, “I said to him, ‘He is not working hard,'” is incorrect because it uses the third person singular pronoun “he” instead of the second person singular pronoun “you.”
The correct sentence should be: “I said to him, ‘You are not working hard.'”