If the chord progression is based off of these chords: Amin Dmin Emin, use the A natural minor scale (also known as relative minor and aoelian).

If the chord progression is based off of Amin Dmin E or E7 use A harmonic minor scale.

If the chord progression is Amin to D or D7 use A dorian.

If the chord progression is Amin to Bb , use A phrygian