As You Stand by the Side of the Road,a Car

Multiple Choice

As you stand by the side of the road,a car approaches you at a constant speed,sounding its horn,and you hear a frequency of 80.0 Hz.After the car goes by,you hear a frequency of 60.0 Hz.What is the speed of the car? The speed of sound in the air is 343 m/s.

A) 64.0 m/s
B) 49.0 m/s
C) 16.0 m/s
D) 36.0 m/s
E) 25.0 m/s