Logic check on minimal information: A is the brother of B and also the brother of C. What is the minimum additional information required to determine the specific relation (brother or sister) between B and C? (i) Gender of C (ii) Gender of B

Introduction / Context:
We know A is a brother of both B and C, so B and C are siblings. The question asks how much additional information suffices to describe the relation between B and C precisely as “brother” or “sister.”

Given Data / Assumptions:

• A is male (brother), and sibling to both B and C.
• We do not know B’s or C’s genders.
• Relation labels (brother/sister) depend on the gender of the subject named first.

Concept / Approach:
Since B and C are siblings, to state “B is brother/sister of C,” we only need B’s gender. Likewise, to state “C is brother/sister of B,” we only need C’s gender. Hence either one of (i) or (ii) alone is sufficient.

Step-by-Step Solution:
If we know B is male → “B is brother of C.” If we know B is female → “B is sister of C.”Alternatively, knowing C’s gender suffices to express “C is brother/sister of B.”

Verification / Alternative check:
We do not need both genders simultaneously since either statement can be framed from either person’s gender alone.

Why Other Options Are Wrong:
Options “Only (i)” and “Only (ii)” each ignore that the other single piece is also sufficient. “Both” overstates the requirement. “None” is incorrect because one of them is indeed sufficient.

Common Pitfalls:
Thinking both genders are needed; they are not if you are content to phrase the relation from the known-gender person’s perspective.

Final Answer:
Either (i) or (ii)