- The formula for the time period \( T \) of a simple pendulum is \( T = 2\pi \sqrt{\frac{L}{g}} \), where \( L \) is the pendulum's length and \( g \) is the acceleration due to gravity. The time period is influenced by \( g \), which is calculated as \( g = \frac{GM}{R^2} \). Here, \( G \) represents the gravitational constant, \( M \) is the planet's mass, and \( R \) is its radius.- Given that the planet's mass and radius are 4 and 2 times that of Earth, respectively, \( g \) will be altered, consequently affecting the time period. Therefore, Assertion (A) is incorrect.- The mass of the pendulum remains constant, which means Reason (R) is correct.Accordingly, the correct option is \( \boxed{(3) (A) \text{ is true but } (R) \text{ is false.}} \).