Step 1: Understanding the Question:
This is a blood relation puzzle. We must deduce the family connection between the speaker, Suresh, and the boy in the picture.
Step 2: Detailed Explanation:
To solve this, decode the statement from the end to the beginning:
1. "my mother": This points to Suresh's mother.
2. "only son of my mother": Because Suresh is a male, he is the only son of his own mother. Thus, this phrase refers to Suresh himself.
3. Replacing this in the original statement gives: "He is the son of Suresh."
This means the boy in the photograph is Suresh's son.
The question asks for Suresh's relationship to the boy. Since the boy is his son, Suresh is the boy's father.
Step 3: Final Answer:
The correct choice is (D).