Doppler Effect is defined as the change of frequency of a sound or light wave produced by a moving source and a stationary observer. The waves when they move towards the object compresses.
The correct answer is:
Option B. lower, decreased
The Dopplereffect can be explained as:
1. The listener will have the impression that the moving source is higher in the pitch as it moves away from the listener.
2. The frequency of the waves will be decreased because the time between the successive sound waves is lengthened or increased.
Therefore, the pitch will be lowered and the frequency will be decreased.
To know more about the doppler effect, refer to the following link:
