A sound consists of four frequencies- 300hz, 600hz, 1200 hz and 2400 hz.A sound 'filter' is made by passing this sound through a bifucated pipe. The sound waves have to travel a distance of 50 cm more in the right branch-pipe than in straight pipe. The speed of sound in air is 300m/s. Then, which of the following frequencies will be almost completely muffled or "silenced" at the outlet?

(A) 300 hz (B) 600 Hz (C)1200 Hz (D)2400 hz