Pointing to a photograph of a girl, Devesh said, "She is my wife's sister's mother's only son's daughter". How is Devesh's wife related to that girl's paternal grandfather?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Daughter
The chain of relations is read one step at a time from Devesh’s wife:
My wife’s sister’s mother is my wife’s mother (sisters share a mother)
Her only son is my wife’s brother
His daughter is the girl in the photograph, so the girl is the daughter of Devesh’s wife’s brother
The girl’s paternal grandfather is her father’s father, that is, the father of Devesh’s wife

So Devesh’s wife is the daughter of the girl’s paternal grandfather.