The diagram below shows a river system consisting of 7 segments, marked P, Q, R, S, T, U, and V. It splits the land into 5 zones, marked Z1, Z2, Z3, Z4, and Z5. We need to connect these zones using the least number of bridges. Out of the following options, which one is correct? Note:

The goal is to connect all the zones with the fewest number of bridges, which requires careful analysis of the river segments that divide the zones. We begin by identifying the critical segments in the river system that can be bridged to ensure access to each zone. In this case, segments \( Q, R, T, \) and \( V \) are the key points where bridges should be placed. These segments allow for the connection of all five zones while keeping the number of bridges to a minimum.
By strategically placing the bridges on these segments, we ensure that every zone is accessible, and the river system remains efficiently connected with the least amount of infrastructure.
Thus, the correct answer is (C).
Eight students (P, Q, R, S, T, U, V, and W) are playing musical chairs. The figure indicates their order of position at the start of the game. They play the game by moving forward in a circle in the clockwise direction.
After the 1st round, the 4th student behind P leaves the game.
After the 2nd round, the 5th student behind Q leaves the game.
After the 3rd round, the 3rd student behind V leaves the game.
After the 4th round, the 4th student behind U leaves the game.
Who all are left in the game after the 4th round?
