In a family of six members A, B, C, D, E and F, A and B are a married couple, with A being the male member. D is the only son of C, who is the brother of A. E is the sister of D. B is the daughter-in-law of F, whose husband has died. In this family, how is C related to B?

Introduction / Context:
This blood relation puzzle describes a six-member family with a married couple, siblings and three generations. The question asks specifically how C is related to B. To answer, you must identify who C's siblings are, who B is married to and where the older generation member F fits in, then translate that structure into a correct relationship term like brother-in-law.

Given Data / Assumptions:

• A and B are a married couple, with A being the male member.
• D is the only son of C, so C is a parent of D and D is male.
• C is the brother of A, so C is male and a sibling of A.
• E is the sister of D, so E is also a child of C.
• B is the daughter-in-law of F, whose husband has died. Thus F is an older female (a widow) and the parent of A (and likely C).
• Since B is married to A, B is a child-in-law of F.

Concept / Approach:
The crucial insight is that C is the brother of A, and B is married to A. The brother of a person's spouse is called a brother-in-law. We must also ensure that there is no alternative role like son-in-law that could apply. Because C is clearly a sibling of A and not a parent of B, the only appropriate relationship description between C and B is brother-in-law.

Step-by-Step Solution:
Step 1: From A and B are a married couple, with A being the male member, conclude that B is the wife of A.Step 2: From C is the brother of A, deduce that C is a male sibling of A.Step 3: From B is the daughter-in-law of F whose husband has died, infer that F is A's mother (since A is male and B is his wife).Step 4: If F is the mother of A and C is the brother of A, C is also a child of F and thus in the same generation as A.Step 5: Because B is married to A and C is A's brother, C is the brother of B's husband.Step 6: The brother of one's spouse is called a brother-in-law, so C is B's brother-in-law.

Verification / Alternative check:
Draw a family tree with F at the top as the widowed mother. She has two sons, A and C. A marries B. C has children D (son) and E (daughter). B, as the wife of A, is F's daughter-in-law and C's sister-in-law. There is no information suggesting that C is married to anyone related to B, or that he is B's child or parent, so no other relation like son-in-law or uncle fits better than brother-in-law.

Why Other Options Are Wrong:
Brother as an answer would be wrong because B and C are not sibling children of the same parents; B married into the family.Son-in-law does not fit because C is not married to F's child; instead C himself is one of F's children.Uncle does not describe the relation between C and B; it might describe how C relates to B's children but not to B herself.None of these is incorrect because brother-in-law exactly matches the described situation.

Common Pitfalls:
One common confusion is between brother and brother-in-law when a person marries into the family. Another mistake is to look at D and E and think about how C relates to them, rather than staying focused on C's relation to B. Always keep the two target persons in mind and work only through the path that connects them directly, instead of wandering through other branches of the tree.

Final Answer:
C is related to B as her Brother-in-law.