The correct answer is: D. None of these
The lady is the person’s sister-in-law.
The person said, “The son of her only brother is the brother of my wife.” This means that the lady’s only brother is the person’s wife’s brother. This makes the lady the person’s wife’s sister. Since the person is married to the lady’s brother’s daughter, the lady is the person’s sister-in-law.
Option A is incorrect because the lady is not the person’s maternal aunt. The person’s maternal aunt is the sister of the person’s mother. The lady is not the person’s mother’s sister, so she is not the person’s maternal aunt.
Option B is incorrect because the lady is not the person’s grandmother. The person’s grandmother is the mother of the person’s mother or father. The lady is not the mother of the person’s mother or father, so she is not the person’s grandmother.
Option C is incorrect because the lady is not the person’s sister of father-in-law. The person’s sister of father-in-law is the sister of the person’s father-in-law. The lady is not the sister of the person’s father-in-law, so she is not the person’s sister of father-in-law.