(i) A, B, C, D, E and F are six members in a family in which there are two married couples.
(ii) D is brother of F. Both D and F are lighter than B.
(iii) B is mother of D and lighter than E.
(iv) C, a lady, is neither heaviest nor the lightest in the family.
(v) E is lighter than C.
(vi) The grandfather in the family is the heaviest.
Which of the following is a pair of married couples ?