Query: Along with hot, soft, urban and Christian AC, what is another prominent time of adult contemporary music?
Context: Over the years, AC has spawned subgenres including "hot AC", "soft AC" (also known as "lite AC"), "urban AC", "rhythmic AC", and "Christian AC" (a softer type of contemporary Christian music). Some stations play only "hot AC", "soft AC", or only one of the variety of subgenres.