Pointing towards a girl, a man said to a woman, “Her mother is the only daughter of your mother.” How is the girl related to that woman?

Pointing towards a girl, a man said to a woman, “Her mother is the only daughter of your mother.” How is the girl related to that woman?

Explanation

The only daughter of woman’s mother is woman herself.

So, the girl is woman’s daughter i.e. the woman is the girl’s mother.