A pendulum has time period T for small oscillations. An obstacle P is situated below the point of suspension O at a distance 3l/4. The pendulum is released from rest. Throughout the motion the moving string makes small angle with vertical. Time after which the pendulum returns back to its initial position is -
(A) T
(B) 3T/4
(C) 3T/5
(D) 4T/5
