An observer is moving towards a stationary source of frequency 320 Hz with a velocity of 10 m/s . The speed of sound in air is 343 m/s . The new frequency heard by the observer is

Question

$(a)\;310 \;Hz\qquad(b)\;336 \;Hz\qquad(c)\;340 \;Hz\qquad(d)\;329 \;Hz$