A Police Radar Device Bounces Radio Waves of Wavelength 3 $\mu$

Multiple Choice

A police radar device bounces radio waves of wavelength 3 mm from the front of a speeding car and measures the Doppler shift in wavelength of the reflected waves. What will be the wavelength shift if the car is moving at 60 mph (80 km/h or 22.2 m/s) (in a 30 mph zone) ? Note that the shift is doubled because of the reflection.

A) 0.44 nm
B) 0.44 $\mu$ m
C) 4.4 $\mu$ m
D) 4.4 m