D is the sister of E. F is the father of D. How is E related to F?

C. CHILD

N is the sister of O. P is the brother of N. How is P related to O?

A. BROTHER

X is the father of Y. Y is the sister of Z. W is the brother of X. How is W related to Z?

A. UNCLE

G is the daughter of H. I is the son of H. How is I related to G?

A. BROTHER

X is the father of Y. Y is the mother of Z. How is Z related to X?

A. GRANDSON/GRANDDAUGHTER