Step 1: Understanding the sentence.
The sentence is in reported speech and needs to be converted into direct speech while maintaining the tense and structure. The original sentence "he was not working hard" is in past continuous tense.
Step 2: Analyzing the options.
(A) I said to him, "You are not working hard." This is incorrect because it doesn't maintain the past continuous tense.
(B) I told to him, "You are not working hard." This is incorrect due to the unnecessary use of "to" after "told."
(C) I said, "You are not working hard." This is also incorrect as it doesn't reflect the original past tense.
(D) I said to him, "He is not working hard." Correct — This option reflects the proper change from indirect to direct speech, keeping the meaning intact.
Step 3: Conclusion.
The correct answer is (D) I said to him, "He is not working hard." as it properly represents the shift from indirect to direct speech.