In family A,B,C,D,E,F: two married couples; D is grandmother of A and mother of B; C is B's wife and F's mother; F is E's granddaughter.
Identify couples.
I. CD
II. DE
III. EB
IV. None

Question: 以下哪项是正确的？
Options:
A. 非 III, B. 仅 I, C. 仅 II, D. 非 II, E. 仅 III
Answer: A
D
True statement: IV