What is the Indirect Speech of "Monir said, 'I must write a letter'?"

• ক Monir said that he must write a letter.
• খ Monir said that he wrote a letter.
• গ Monir said that he has to write a letter.
• ঘ Monir said that he had to write a letter. ✅ সঠিক উত্তর