I introduced a lady: “She is the mother of the only daughter of my son's father-in-law.” How is she related to me?
A. She is my sister
B. She is the mother in law of my son
C. She is my son's aunt
D. She is the wife of my son's father in law
E. She is my mother
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → B, D Only
The description is unwound from the end, one relation at a time:
My son’s father-in-law is the father of my son’s wife.
His only daughter is therefore my son’s wife.
The lady is the mother of my son’s wife, that is, my son’s mother-in-law, and the wife of my son’s father-in-law.

A. She is my sister Incorrect. She is from my son’s wife’s family; nothing makes her related to me by birth.
B. She is the mother in law of my son Correct. She is the mother of my son’s wife.
C. She is my son’s aunt Incorrect. An aunt is a sister of a parent; she is the mother of his wife.
D. She is the wife of my son’s father in law Correct. Her daughter’s father is my son’s father-in-law, so she is his wife.
E. She is my mother Incorrect. My mother would be my son’s grandmother, not the mother of his wife.