Adult contemporary music:

Other popular names for the format include "Warm", "Sunny", "Bee" (or "B") and (particularly in Canada) "EZ Rock". The format can be seen as a more contemporary successor to and combination of the middle of the road (MOR), beautiful music, easy listening and soft rock formats. Many stations in the soft AC format capitalize on its appeal to office workers (many of them females aged 25–54, a key advertiser demographic), and brand themselves as stations "everyone at work can agree on" (KOST originated that phrase as a primary tagline, and other soft AC stations have followed suit).

Please answer a question about this article. If the question is unanswerable, say "unanswerable". Along with MOR, easy listening and soft rock, what format is soft adult contemporary a successor to?
beautiful music