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 76 Hz. After the car goes by, you hear a frequency of 65 Hz. What is
The speed of the car? The speed of sound in the air is 343 m/s.

A) 29 m/s
B) 27 m/s
C) 30 m/s
D) 26 m/s
E) 28 m/s