2. A pendulum of length L has its motion interrupted by a peg vertically beneath the support at a distance y below support, see Fig. 1. The bob is released when the string is horizontal.What is the minimum value of y for the bob to swing in a complete circle?(A) L/2 ； (B) 2L/3； (C) 3L/4 ；(D) 3LI5；(E) None.