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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This question is asking which two rounds together make up both of Green's matches in the tournament. Since the full schedule is fixed as Round A: Red vs Blue, Round B: Green vs Yellow, Round C: Green vs Blue, and Round D: Red vs Yellow, each option can be checked directly against this table rather than re-deriving the rules.
Since every team plays exactly two matches across the four rounds, and Green's name appears only in Round B and Round C of the fixed schedule, those are the only two rounds where Green actually takes the field.
So the correct answer is Round B and Round C.
Instead of unpacking Rule 3's wording directly, this option list can be settled by working out which two rounds belong to Red and which two belong to Blue, then finding where those sets overlap.
Only the third pairing survives this check: the round where Red's schedule and Blue's schedule overlap is Round A, so that has to be the Red vs Blue match.
So the correct answer is Red vs Blue.
Blue's first opponent can be pinned down by checking every named option against the order of the four rounds, rather than just reading off the schedule once.
Since Round A comes before Round C and Round A's match is Red against Blue, Red is confirmed as the first team Blue plays.
So the correct answer is Red.
The match in Round C can be confirmed by checking which teams are already committed elsewhere and ruling out any option that repeats one of those commitments.
Round C is the only round where Green's and Blue's remaining slots line up, so that round has to be Green against Blue.
So the correct answer is Green vs Blue.
The pair of Yellow-free rounds can be found by checking which rounds are filled entirely by the other three teams, based on the fixed schedule.
Only Round A and Round C are completely free of Yellow's matches once every round is checked against the fixed schedule.
So the correct answer is Round A and Round C.
Checking which team Yellow never meets is a matter of listing Yellow's two actual matches and comparing the leftover team against each option.
Since Yellow's two matches are used up entirely by Green and Red, Blue is the one team left that Yellow never faces.
So the correct answer is Blue.
Changing Round D to Blue vs Yellow can be checked against each rule one at a time to see which one it actually breaks.
Only Rule 5 depends on Red actually appearing in Round D alongside its non-Blue opponent, and that is exactly the condition the swap destroys.
So the correct answer is Rule 5 (Opponent Link).