Correct option is C
Pendulum clocks are highly sensitive to changes in temperature. During the summer, the length of the pendulum increases due to the expansion of the metal rod caused by the rise in temperature. An increase in the pendulum's length results in a longer period of oscillation (swinging). Since the pendulum takes a longer time to complete each oscillation, the clock slows down. This phenomenon is based on the principle that the period of a pendulum is directly proportional to the square root of its length. Hence, when the length increases, the period (or the time taken for one complete swing) also increases, causing the clock to run slower.
