Which phenomenon explains why a person standing on a railway platform hears a higher pitch as a train whistles and approaches them?

Correct answer: Doppler Effect

Explanation: ✅ Correct Answer: B) Doppler Effect 📚 Explanation: The Doppler Effect is the change in the frequency of a wave in relation to an observer who is moving relative to the wave source. As the train moves toward the observer, the sound waves are "compressed," leading to a higher perceived frequency (pitch). Once the train passes and moves away, the waves are "stretched," and the pitch drops.