Pointing to a man, a girl said, "He is the brother of my grandmother's only child's husband's only brother." How is the man related to the girl?

Correct option is A

"He is the brother of my grandmother's only child's husband's only brother."
Break it clearly:
Grandmother's only child → Girl’s parent (since grandmother has only one child).
That parent must be the girl’s father or mother.
Parent’s husband → If grandmother's only child is mother → her husband = girl’s father.
So grandmother's only child's husband = girl’s father.
Now:
Father's only brother → girl’s uncle.
The man is brother of that uncle.
So he is also brother of father.
Hence, he is also father (since brothers).
Thus, the man is girl's father.
Correct Answer: (A) Father