In a family, there are 6 members P, Q, R, S, T and U. • P and Q are a married couple • R is the son of P • T is the sister of R • Q is the mother of S U is the brother of PWho is the father of S?

Correct — A.
Rule: fix each person's gender first, then read a mother's husband as the father.

Q is the mother of S, so Q is female.
P and Q are a married couple, so P is Q's husband.
S's mother is Q and Q's husband is P, so P is S's father.

P → option (a).

Why the others are wrong

• (b)
  Q — Q is S's mother, as the stem states. A mother cannot be the father, so Q is out at once.
• (c)
  U — U is the brother of P, the father. That makes U S's paternal uncle, not S's father.
• (d)
  R — R is the son of P, and P is S's father, so R is S's brother. A sibling cannot be the father.

Blood-relation items give a list of links and ask for one relation. Draw a small tree: couples side by side, children below.

Here P and Q sit at the top as a couple. R, T and S are P's children, and U stands beside P as his brother. Once Q is known to be female (she is S's mother), P must be the husband, and the tree answers the question.

Key facts

• A mother's husband is read as the child's father.
• A father's brother is the child's paternal uncle.
• Children of the same father are siblings.

Common traps

• Marking U because he is a male of P's generation, when he is P's brother
• Leaving P's gender open because the stem never uses the word husband

No directly related past PYQ was found.