The potential energy of a particle of mass m at a distance r from a fixed point O is given by V (r) = kr/2, where k is a positive constant of appropriate dimensions. This particle is moving in a circular orbit of radius R about the point O. If v is the speed of the particle and L is the magnitude of its angular momentum about O, which of the following statements is (are) true? (A) V= k -R 2m (C) L=mkR (B) v = (D) L= -R m mk R