Answer:
C. will have a higher frequency if the ambulance siren is moving towards the observer.
Explanation:
A) it is wrong
Source moving towards the observer, observer will listen higher frequency.
B) Again wrong
Source is moving away from observer, observer will hear lower frequency.
C) correct.
will have a higher frequency if the ambulance siren is moving towards the observer
D) Wrong as pitch is equivalent to frequency
Source moving towards the observer, observer will listen higher pitch.
E) wrong
will have shorter wavelength because the frequency increases.
only C is correct.