For a simple pendulum, a graph is plotted between its kinetic energy (KE) and potential energy (PE) against its displacement d. Which one of the following represents these correctly?

In an SHM, variation of potential energy with displacement d is given by P.E (y) = 1/2kd², which represents the equation of a straight parabola with vertex at d=0. And variation of kinetic energy with displacement d is given by K.E (y) = 1/2k(a² - d²), which represents the equation of an inverted parabola with vertex at d=a. Here a is the amplitude of the SHM. Hence the correct choice is B.