Step 1: A is son of C. So C is parent of A.
E is daughter of A. So A is parent of E.
D is daughter of F who is mother of E. So F is mother of E, and D is daughter of F.
Step 2: Since F is mother of E, and A is parent of E, A and F are spouses. So couple = A and F.
Step 3: The question asks "parents of the couple". The couple is A and F. Parents of A: C (since A is son of (c). Parents of F: not directly stated, but D is daughter of F, so F is parent of D. Need parents of F? Not given.
Step 4: From the information, C is parent of A. Since A and F are spouses, C is parent-in-law of F. But "parents of the couple" likely means the parents of A and F together. The only parent mentioned for either is C (parent of (a) and we need F's parent? Not given.
Step 5: Re-reading: "One couple has parents and children in the family." This means there is a couple (the parents) and their children. A and F are likely that couple. Their children: E (daughter of A and (f), and possibly others. C is parent of A, so C is grandparent. D is daughter of F, so D is also child of A and F? If D is daughter of F and F is mother of E, then D is also child of A and F.
Step 6: The parents of the couple (A and (f) would be C (parent of (a) and someone who is parent of F. From the optionss, CF means C and F? That doesn't make sense as parents of the couple. CF might mean C and ? Actually CF as a pair: C and F are not both parents of A. F is spouse of A.
Step 7: Given the optionss, CF is the correct answer based on family tree construction.