Pointing toward a person in a photograph, Anjali said "He is the only son of the father of my sister's brother."
How is that person related to Anjali ?

Answer: E. None of these

The relations may be analysed as follows :
Sister's brother -- Brother;
Brother's father -- Father;
Father's son -- Brother.
So, the person in the photograph is Anjali's brother.
Hence, the answer is (e).