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).
Shown on the left is a set of equations. Which option belongs to the same set? 
Shown below is an arrangement of closely stacked spheres. Assume each one to be in contact with its immediate neighbour. What is the total number of points where the spheres touch each other?
The 12 musical notes are given as \( C, C^\#, D, D^\#, E, F, F^\#, G, G^\#, A, A^\#, B \). Frequency of each note is \( \sqrt[12]{2} \) times the frequency of the previous note. If the frequency of the note C is 130.8 Hz, then the ratio of frequencies of notes F# and C is: