I want to know the answer to the following question:
Along with Frank Sinatra, Doris Day, Johnny Mathis, Nat King Cole, and Perry Como, who was a prominent early adult contemporary radio artist?
All the background I'm provided with is that "The custom recordings were usually instrumental versions of current or recent rock and roll or pop hit songs, a move intended to give the stations more mass appeal without selling out.". Is that enough to answer the question?