A is the brother of B. C is the sister of B. D is the father of C. How is D related to A?
- (a)Father
- (b)Uncle
- (c)Brother
- (d)Grandfather
Answer
Why
Correct — A.
Rule: siblings share a father, so the father of one is the father of all.
A is B's brother and C is B's sister → A, B and C are siblings.
D is C's father → D is also the father of B and of A.
D is A's father → option (a).
Why the others are wrong
- (b)Uncle — Uncle would make D the brother of A's parent. D is the parent himself: he is C's father, and C is A's sister.
- (c)Brother — Brother puts D in A's generation. A father stands a generation above his children, and D is the father of A's sister C.
- (d)Grandfather — Grandfather is two generations up. D is C's father and C is A's sister, so D stands just one generation above A.
Concept
Solve a blood-relation chain by generation and gender. Brothers and sisters of the same person stand in one generation, and a father stands one generation above.
Here the first two sentences put A, B and C side by side as siblings. The third puts D one level above C, and so above A and B too.
D's relation is given to C, not to A. The link to A runs through B: A and C are both B's siblings, so they share D as father.
Key facts
- A is B's brother and C is B's sister, so A, B and C are siblings.
- D is C's father, so D is the father of A and B as well.
Study next
Common traps
- Treating D as related to C alone and not carrying the link across to A
- Reading 'D is the father of C' as 'C is the father of D'
16 Sep 2025, 12:30, Reasoning Q.4 turns on the same step, a sibling sharing the parent: A is B's brother and B is C's daughter, so A is keyed C's son (option b).
19 Sep 2025, 09:00, Reasoning Q.22 carries a sibling chain down a generation: A, B and C are siblings and C is D's father, so A is keyed D's Uncle.
Related PYQs
No directly related past PYQ was found.