At which place does the motion of a pendulum become fastest?

Explanation

The key concept to understand in this question is the relationship between the acceleration due to gravity (g) and the motion of a pendulum. The motion of a pendulum is fastest where the acceleration due to gravity is greatest. This acceleration varies with the distance from the center of the Earth. Therefore, at locations closer to sea level, where the value of g is higher, the pendulum's motion would be fastest. Since Karachi is a coastal city at sea level, it experiences a higher value of g compared to higher altitudes like K-2 and Murree, making it the correct answer. K-2 and Murree, being at higher altitudes, would have lower values of g, resulting in slower pendulum motion. Lahore, although at a lower altitude than K-2 and Murree, doesn't have a specified value for g, making it difficult to determine definitively if it has the fastest motion.