Pointing towards a man, a woman said, “His mother is the only daughter of my mother.” How is the woman related to the man?

The correct answer is C. Sister.

The woman’s mother has only one daughter, who is the man’s mother. This means that the woman and the man are siblings.

Option A is incorrect because the woman is not the man’s mother.

Option B is incorrect because the woman is not the man’s grandmother. The man’s grandmother is the woman’s mother’s mother.

Option D is incorrect because the woman is not the man’s daughter. The man’s daughter is the woman’s niece.