Question

what is an increase (or decrease) in the frequency of sound, light, or other waves as the source and observer move toward (or away from) each other.

Explanation:

The Doppler Effect is defined as the change (increase or decrease) in the frequency of sound, light, or other waves as the source and the observer move relative to each other. When they move towards each other, the frequency increases, and when they move away, the frequency decreases.

Answer:

B. Doppler Effect