Which of the following sentence contains the word 'why' as relative adverb?

• কI don't know why and wherefore of it.
• খWhy did he come here?
• গI don't know the reason why he did it.
• ঘWhy, it is surly Mahboob.

✅ সঠিক উত্তর: গ. I don't know the reason why he did it.