A source of sound, emitting frequency of 300 Hz, moving towards a stationary reflecting wall with speed 50 m/sec. There are five observes A,B,C,D and E as shown in figure. Speed of sound is 350 m/sec.
(A) The beat frequency appeared to observer A is zero
(B) The beat frequency appeared to observer B is 20 Hz
(C) The beat frequency appeared to observer E is 20 Hz :
(D) The beat frequency appeared to observer B is 10 Hz