A Bell Is Ringing Inside of a Sealed Glass Jar

Multiple Choice

A bell is ringing inside of a sealed glass jar that is connected to a vacuum pump. Initially, the jar is filled with air. What does one hear as the air is slowly removed from the jar by the pump?

A) The sound intensity from the bell gradually decreases.
B) The frequency of the sound from the bell gradually increases.
C) The frequency of the sound from the bell gradually decreases.
D) The speed of the sound from the bell gradually increases.
E) The intensity of the sound from the bell does not change.