Eight persons P, Q, R, S, T, U, V and W sit around a round table in eight different seats placed with equal distance between any two consecutive seats. Both P and R are adjacent to Q. Both T and R are adjacent to S. Both U and W are adjacent to V. S and W are on opposite chairs. If while going in the clockwise direction around the table from P, one meets R before T, then how many persons shall Q cross while moving in the clockwise direction around the table before meeting W?

Correct Option Analysis (Option A): This problem is a classic circular arrangement puzzle characteristic of the UPSC Civil Services Aptitude Test (CSAT) Paper-II.

1. Forming the Primary Block: The statement "Both P and R are adjacent to Q" yields the sequence P-Q-R or R-Q-P. Similarly, "Both T and R are adjacent to S" yields T-S-R or R-S-T. Merging these overlapping segments at 'R' generates a five-person block: P-Q-R-S-T or T-S-R-Q-P.
2. Determining Direction: The condition dictates that moving clockwise from P, one meets R before T. If the clockwise order were T-S-R-Q-P, starting from P would mean meeting T before R. Therefore, the strict clockwise sequence must be P-Q-R-S-T. Let us assign them seats 1 through 5 respectively.
3. Placing the Remaining Persons: S is seated at position 4. In an equal-distance 8-seat circular arrangement, the opposite seat is mathematically separated by exactly three chairs (Position + 4). Thus, the seat opposite S (4) is 8. The puzzle specifies S and W are opposite, locking W at seat 8.
4. Completing the Circle: "U and W are adjacent to V" dictates the sequence U-V-W. With W at 8 and P already at 1, V must occupy seat 7 and U must occupy seat 6. The final clockwise arrangement is P(1), Q(2), R(3), S(4), T(5), U(6), V(7), W(8).
5. Calculating the Crossings: Moving clockwise from Q (seat 2) to W (seat 8), Q crosses R(3), S(4), T(5), U(6), and V(7). This totals exactly 5 persons, making Option A correct.

Wrong Options Analysis:

• Option B (4): Incorrect due to a potential arithmetic counting error; the block between Q and W contains exactly 5 persons, not 4.
• Option C (2): Incorrect because it severely underestimates the consecutive block of persons separating Q and W.
• Option D (1): Incorrect as this specifically represents the number of persons Q would cross if moving in the counter-clockwise direction (crossing only P at seat 1 to reach W at 8), violating the question's prompt.

Takeaway: In circular logical arrangements, isolate and merge overlapping adjacent elements into a single macro-block first, then apply directional (clockwise/anti-clockwise) and geometric constraints (opposites) to lock the final positions.