Confidence in the Correctness of the Answer for the Previous

Multiple Choice

Confidence in the correctness of the answer for the previous question can be increased by recognizing that

A) if the emitter moves toward the receiver with a speed equal to that of sound, the frequency received is very large indeed.
B) if the receiver moves away from the emitter with a speed equal to that of sound, the frequency received is very small indeed.
C) both of the first two answers are relevant to the choice of the correct answer to the previous question.
D) none of the above.