P is the brother of Q and R. S is R's mother. T is P's father.
Which of the following statements cannot be definitely true ?

E. Q IS T'S SON.

A family consists of six members P, Q, R, S, T and U. There are two married couples. Q is a doctor and the father of T. U is grandfather of R and is a contractor. S is grandmother of T and is a housewife. There is one doctor, one contractor, one nurse, one housewife and two students in the family. Who is the husband of P ?

C. Q

A man and his wife have three sons, and every of the sons has a sister. How many are there in the family ?

C. 6

(I).   A, B, C, D, E and F are six members of a family.
(II).  One couple has parents and their children in the family.
(III). A is the son of C and E is the daughter of A.
(IV). D is the daughter of F who is the mother of E. What relationship do D and E bear to each other ?

D. SISTER

E is the son of A.
D is the son of B.
E is married to C.
C is B's daughter.
How is D related to E ?

D. BROTHER-IN-LAW