In the following question, a sentence has been given in Direct/Indirect speech. Out of the four alternatives suggested, select the one which best expresses the same sentence in Indirect/Direct speech. My sister said to me, "You didn't help me yesterday so I will not help you now."

• My sister said to me that I had not helped her the day before so she would not help me then.
• My sister said to me that I have not helped her the day before so she would not help me now.
• My sister said to me that I have not helped her yesterday so she would not help me then.
• My sister said to me that I had not helped her yesterday so she would not help me now.