If A is the brother of B, B is the sister of C, and C is the father of D, how is A related to D?

Correct — A.
Rule: fix each person's gender and generation, then compare A with D.

A is B's brother → A is male, a sibling of B.
B is C's sister → C is a sibling too, so A, B and C are one generation.
C is D's father → D is one generation below.

A is the brother of D's father → D's uncle, option (a).

Why the others are wrong

• (b)
  Father — Father is C's relation to D. A and C are named separately, so A is C's brother, not D's father.
• (c)
  Brother — Brother would put A in D's generation. A is a sibling of D's father, one generation above D.
• (d)
  Cousin — Cousin is what A's own children would be to D. A himself is a generation up, as the father's brother.

For a chain of relations, record gender and generation at each link. Brother, sister and father each fix a gender. A sibling link keeps two people in the same generation. A parent link moves one generation down.

Here A, B and C are siblings, and D is C's child. The brother of a person's father is that person's paternal uncle.

Key facts

• Father's brother = paternal uncle. Mother's brother = maternal uncle.
• A sibling of your parent is one generation above you.
• The child of your parent's sibling is your cousin.

Common traps

• Missing that 'B is the sister of C' makes C a sibling of A as well
• Carrying C's link to D over to A and answering Father

No directly related past PYQ was found.