Correct Answer - Option 3 : F
Six people A, B, C, D, E and F participated in the debate.
i) Two of the six were women.
ii) E and his unmarried sister were the new members in this year's debate, D's husband who was the winner of the previous year and participating in this year's debate.
iii) A and C were last year's runners-up, this year's winner is neither previous year's winner, nor new member
iv) B has left the debate midway due to unavoidable reason
v) C at the end of the debate got more marks than A but less than E and F.
F > E > C > A
Now,
E's sister is the new member of the competition. It is clear from the question that in the previous competition A, C, and D have participated.
Thus 'F' will be the sister of 'E'.
Hence, the correct answer is "F".