In Relation puzzle type, mutual blood relations or other information of more than two persons are mentioned and information about any two is mentioned.
There are six children playing football namely A, B, C, D, E and F.
A and E are brothers. F is the sister of E. C is the only son of A's uncle.
B and D are the daughters of the brother of C's father
How is C related to F ?
F is E's and hence A's sister.
So, C is also the son of F's uncle and is, therefore, F's cousin.
So, the answer is (a).