Explanation:

- Start by breaking down the statement: "His daughter’s brother is my mother’s son’s brother."

- "His daughter’s brother" refers to the man’s son.

- "My mother’s son’s brother" refers to Rohan's brother.

- Therefore, the man's son is Rohan's brother.

- Based on this information, the man is Rohan's father.

- Let’s explore the options:

1. Father's father - This would be Rohan's grandfather.

2. Father's brother - This would be Rohan's uncle.

3. Brother - This implies they share the same parents, but the description identifies the man as having a daughter's brother, i.e., not just any brother.

4. Father - The man's son is Rohan's brother, meaning the man is Rohan's father.