When a sound source is moving toward the observer, the observer will hear

Atoy airplane, flying in a horizontal, circularpath, completes 10. complete circles in 30.seconds. if the radius of the plane’s circular pathis 4.0 meters, the average speed of the airplane is(1) 0.13 m/s (3) 1.3 m/s(2) 0.84 m/s (4) 8.4 m/s