Sound of a known frequency, wavelength, intensity, and speed travels through air and bounces off an imperfect reflector which is moving toward the source. Which properties of sound remains the same before and after reflection? Speed, intensity, frequency, or wavelength?

A) Speed

Explanation:

The medium of transmission (air) does not change before and after reflection. The sound still travels in air after the reflection. i. e the medium of transmission of sound is constant.

Since the medium of transmission remains constant, speed also remains constant. Speed only changes when the medium of transmission changes.