As sounds become louder, their ______ increases.

A) frequency
B) pitch
C) amplitude
D) hertz

Amplitude

In the context of waves, it is the height of the wave, which can determine the intensity or loudness of a sound.

Frequency

The rate at which something occurs or is repeated over a particular period of time or in a given sample.

Pitch

In acoustics, it is the quality of a sound governed by the rate of vibrations producing it; the degree of highness or lowness of a tone.