What is the minor key with no sharps or flats?

The minor key with no sharps or flats is A minor. This can be understood by recognizing the key signature of A minor, which is the relative minor of C major. Both C major and A minor share the same key signature, which consists of no sharps or flats.

In music theory, the relative minor key is determined by starting from the sixth degree of the major scale. In the case of C major, the sixth degree is A, making A minor its relative minor. This is vital for understanding key signatures and relationships between major and minor keys.

Other options involve minor keys that do contain sharps or flats in their key signatures. C minor has three flats, E minor has one sharp, and D minor has one flat, which distinguishes them from A minor, solidifying A minor as the correct answer.