Seven persons P, Q, R, S, T, U and V participate in and finish all the events of a series of swimming races. There are no ties at the finish of any of the events. V always finishes somewhere ahead of P. P always finishes somewhere ahead of Q. Either R finishes first and T finishes last or S finishes first and U or Q finishes last. If in a particular race V finished fifth, then which one of the following would be true?

Here is the explanation for why option A is correct:

The problem establishes a specific finishing order for three participants: V must finish ahead of P, and P must finish ahead of Q. This creates a chain of V then P then Q.

If V finishes fifth in a particular race, then P must finish sixth and Q must finish seventh because there are only seven participants and both P and Q must finish after V.

The rules state that if Q finishes last, then S must finish first. Since Q finished seventh and therefore last in this specific race, the condition for S finishing first is triggered.

Option A is correct because S must finish first according to the given rules. Options B, C, and D cannot be determined as true based on the provided constraints.