NIMCET 2012 — Reasoning PYQ

Step 1: Analyze the given statements

1. $A$ is brother of $B$: This means $A$ is Male $(A^{+})$. $A$ and $B$ are siblings.

2. $C$ is brother of $B$: This means $C$ is Male $(C^{+})$. $C$ and $B$ are siblings.

3. $A$ is brother of $D$: This means $A$ and $D$ are siblings.

Step 2: Determine the relationships

From the above points, we know that $A,B,C,$ and $D$ are all siblings (children of the same parents).

• Known Genders: $A$ is Male $(+)$, $C$ is Male $(+)$.

• Unknown Genders: $B$ and $D$ could be either Male or Female.

Step 3: Evaluate the options

• (a) $A$ is brother of $C$: Since $A$ is male and they are siblings, this must be true.

• (b) $B$ is brother of $C$: We don't know $B$'s gender. $B$ could be the sister of $C$.

• (c) $D$ is brother of $C$: We don't know $D$'s gender. $D$ could be the sister of $C$.

• (d) $B$ is brother of $D$: We don't know the gender of $B$ or $D$.

Conclusion:

The only statement that is definitely true regardless of the unknown genders is that $A$ is the brother of $C$.

Correct Option: (a) $A$ is brother of $C$