When someone says distributor what is that party also known as in music? Examples? What do they do?

a) Label; Sony Music, Universal Music Group; They distribute music to various platforms.
b) Manager; Scooter Braun, Irving Azoff; They handle the artist's career.
c) Agent; Creative Artists Agency, William Morris Endeavor; They book shows and appearances.
d) Publisher; Warner Chappell Music, Sony/ATV Music Publishing; They represent songwriters.