Q is the daughter of R, who is the mother of S. T is the father of Q. How is T related to S?

Correct — D.
Rule: place everyone on one family tree, then read T's line to S.

R is the mother of Q and of S, so Q and S are siblings.
T is Q's father, so T is R's husband.
T is therefore S's father → option (d).

Why the others are wrong

• (a)
  Son — Son reverses the generations. T is Q's parent and Q is S's sibling, so T sits above S, not below.
• (b)
  Husband — Husband is T's relation to R, the mother. The question asks about S, R's child.
• (c)
  Brother — Brother would put T in S's generation. As Q's father, T is one generation above both Q and S.

Chain statements are easiest on a small tree: parents on the top row, children below. Here R goes on top with Q and S beneath her, and T joins R on the top row as Q's father.

Once Q and S hang from the same couple, T's relation to S is the same as his relation to Q: father. S's gender is never given, and it does not matter, because father is the same word for a son or a daughter.

Key facts

• R is the mother of both Q and S, so Q and S are siblings.
• T, as Q's father, is R's husband and S's father.
• Father is the answer whether S is a son or a daughter.

Common traps

• Answering Husband, which is T's relation to R, not to S
• Stalling because S's gender is not given, when the answer does not need it

No directly related past PYQ was found.