Pointing to a photograph of a boy Suresh said, “He is the son of the only son of my mother.” How is Suresh related to that boy?

The correct answer is: Cousin.

Suresh’s mother has only one son, who is the boy’s father. This means that Suresh and the boy are first cousins.

A brother is a male sibling. An uncle is a male relative of a person’s parent, especially one who is older than the person. A father is a male parent.

In this case, Suresh is not the boy’s brother, uncle, or father. He is the boy’s cousin.