Correct Answer: I said to you, “I bought a new book for you yesterday.”

Solution : The third option is correct.

Explanation:
Direct speech, also known as quoted speech or direct discourse, refers to the representation of someone's words or statements exactly as they were spoken.
Narration conversion:

• The reporting verb "told" changes to "said to".
• The past perfect tense "had bought" changes to the simple past tense "bought".
• "The day before" becomes "yesterday" in the direct speech part.
• The second person pronoun "you" remains the same as the indirect part.

Therefore, the direct form would be: I said to you, "I bought a new book for you yesterday ."