Answer:
pitch
Explanation:
Rhythm is, by definition, a strong, regular, repeated pattern of movement or sound. This means that it's a pattern of one thing.
Out of beat, pitch, tempo, and meter, three of them have one thing in common when corresponding to rhythm: monotony. Monotony is the same thing, unchanged in sound and movement.
For example, drawing a straight line continuously.
Beat is a main accent or rhythmic unit in music or poetry.
Pitch is the degree of highness or lowness of a tone.
Tempo is the speed at which a passage of music is or should be played.
Meter is the rhythm of a piece of poetry, determined by the number and length of feet in a line.
When you listen to music, a rap, or poetry, you can "feel the beat." This means you can pick out the main sound being accentuated, like the "boom-boom-boom" or a clapping track.
Tempo is how fast something goes. A slow song played at a ballet may be different than a rap song, which is fast. Tempo is the speed.
Meter is the rhythm, usually in poetry. It's like a beat and other patterns in the poem.
Pitch is the one that is different. It changes the tone. For example, a high note vs. a low note. That's pitch. When someone swallows helium and talks, their voice is now "high-pitched" because it has a higher-sound tone.
Rhythm does not change—it's a pattern of beats, tempos, and rhythms. Unlike pitch, pitch is musical. Rhythm is not—it's just the pattern.