A source producing sound of frequency $170 \; Hz$ is approaching a stationary observer with a velocity of $17\;ms^{-1}$. The apparent change in the wavelength of sound heard by the observer is : (speed of sound in air = $340\; ms^{-1}$)

Question

( A ) 0.4 m
( B ) 0.2 m
( C ) 0.1 m
( D ) 0.5 m