What describes a nonharmonic tone that steps between two chords?

The correct answer is a passing tone, which is a nonharmonic tone that connects two chord tones by stepping between them. In music, passing tones serve as a way to create smooth melodic lines and are typically approached by a step from one chord tone and resolved by a step to another chord tone.

When the melody steps down or up to a nonharmonic tone and then resolves to a chord tone in the next chord, it adds a fluid and cohesive quality to the music. This motion creates what is often referred to as a "passing" movement between the harmonies, making it integral to many musical phrases.

In contrast, anticipation refers to a note that is played before it becomes part of the harmony, pivotal tone usually relates to a single note that defines the change of harmony without stepping between them, and neighboring tones, also called auxiliary tones, move away from a chord tone and return back to it.