What minor key is characterized by 4 flats?

The key that is characterized by 4 flats is F minor. In music theory, the key signature corresponds to the number of flats or sharps present in a scale, which indicates the tonal center of a piece of music.

F minor is the minor key that features B♭, E♭, A♭, and D♭ as its flats, aligning it with the specified characteristic of having 4 flats. This signature defines the scale of F minor, making it essential for compositions that are rooted in this key to utilize this particular set of notes.

When looking at the other keys mentioned, C minor features 3 flats (B♭, E♭, A♭). C# minor has 4 sharps, while A minor typically has no sharps or flats unless altered by a modal change. Therefore, the presence of 4 flats uniquely identifies F minor, making it the correct answer to the question posed.