The correct answer is Cousin.
Lata’s grandfather has only one son. This son is Lata’s father. The man in the photograph is the son of Lata’s father. This makes him Lata’s cousin.
Option A is incorrect because Lata’s father is the only son of Lata’s grandfather. This means that Lata does not have a brother.
Option B is incorrect because the man in the photograph is the son of Lata’s father, not her grandfather. This means that he is not Lata’s uncle.
Option D is incorrect because the question provides enough information to determine the relationship between Lata and the man in the photograph.