In alphabet series, some alphabets are missing which are given in that order as one of the alternatives below it. Choose the correct alternative. -
a _ bc _ a _ bcda _ ccd _ bcd _
All the six members of a family A, B, C, D, E and F are travelling together. B is the son of C but C is not the mother of B, A and C are a married couple. E is the brother of C. D is the daughter of A. F is the brother of B.
Which of the following is a pair of females ?