Correct Answer & Explanation
Option C
Let's break down the statement from the man's perspective:
• "My wife's brother" means the man's brother-in-law.
• "The son of her only brother is the brother of my wife." This means the lady's nephew is the man's brother-in-law.
• If the lady's nephew is the man's brother-in-law, it implies the lady's brother is the father of the man's wife.
• So, the lady's brother is the man's father-in-law.
• Therefore, the lady is the sister of the man's father-in-law.