P, Q, R, S, W, X, Y, Z are seated around a circle facing the centre. The husband of Z is second to the right of Q who sits between two males. X sits second to the left of the daughter of S. X is the sister of Y and not an immediate neighbour of Z's husband. Only one person sits between P and X. P is the father of Y. S (brother of Z) sits to the immediate left of his mother. Only one person sits between Z's mother and W. Only one person sits between Z and Y. Y is the mother of R and not an immediate neighbour of W. Which of the following is true?
In circular family-seating puzzles, lock the role edges first (e.g., "husband of Z second right of Q", "S left of his mother"), then place gendered roles ("between two males"). Finally, use "exactly one person between" constraints to force a unique ring.
Step 1: Decode fixed relations and genders.
Z is female; S is Z's brother $\Rightarrow$ S is male.
X is sister of Y $\Rightarrow$ X, Y are females.
P is the father of Y $\Rightarrow$ P is male.
Y is the mother of R $\Rightarrow$ Y female, R child.
Let the husband of Z be one of the males.
Step 2: Start with the "Q and Z's husband" condition.
"The husband of Z is second to the right of Q" and "Q sits between two males."
Place $Q$ and ensure both neighbours of $Q$ are males; put $Z$'s husband two seats to $Q$'s right.
Step 3: Use the S-mother and “daughter” clues.
"S sits to the immediate left of his mother" $\Rightarrow$ the person to the right of $S$ is Z's mother.
"X sits second to the left of the daughter of $S$" and "X$\,\not\,$adjacent to Z's husband". Together with "Only one person between $P$ and $X$" fixes $X$ and hence $S$'s daughter as $W$ (female).
Step 4: Complete the circle consistently.
A unique consistent arrangement (up to rotation) is: \[ \boxed{P \;-\; Y \;-\; X \;-\; Z \;-\; W \;-\; S \;-\; Q \;-\; R \;-\; (back~to~P)} \] with all facing the centre, and $P$ is the husband of $Z$.
Check all clues: $Q$ between two males $(S,R)$; Z's husband ($P$) is second right of $Q$; $X$ is second left of $W$ (the daughter of $S$); $X$ is not adjacent to $P$; exactly one between $P$ and $X$; exactly one between $Z$ and $Y$; $Y$ not adjacent to $W$; $S$ is immediately left of his mother $Q$; exactly one between $Q$ (Z's mother) and $W$. All satisfied.
Step 5: Evaluate the options.
(a) $R$ and $W$ are not cousins (from the family tree, $W$ is $S$'s daughter; $R$ is $Y$'s child; $Y$ is (most naturally) $P$-$Z$'s daughter) $\Rightarrow$ False.
\(\hspace{2cm}\) Even without assuming mothers, the arrangement makes (a) not necessarily true.
(b) From Step 4, the mother of $S$ and $Z$ is $Q$ $\Rightarrow$ True.
(c) Z is not third to the left of her daughter (neither $Y$ nor $X$ fits) $\Rightarrow$ False.
(d) $R$ has $Q$ (female) as one neighbour $\Rightarrow$ False.
Hence (b) is correct.
Four teams – Red (R), Blue (B), Green (G), and Yellow (Y) – are competing in the final four rounds of the Inter-School Science Olympiad, labeled Round A, Round B, Round C, and Round D. Each round consists of one match between two teams, and every team plays exactly two matches. No team plays the same opponent more than once.
The final schedule must adhere to the following rules:
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