Task: Question Generation
Input (English): Mainstream AC itself has evolved in a similar fashion over the years; traditional AC artists like Barbra Streisand, the Carpenters, Dionne Warwick, Barry Manilow, John Denver, and Olivia Newton-John found it harder to have major Top 40 hits as the 1980s wore on, and due to the influence of MTV, artists who were staples of the Contemporary Hit Radio format, such as Richard Marx, Michael Jackson, Bonnie Tyler, George Michael, Phil Collins, and Laura Branigan began crossing over to the AC charts with greater frequency. Collins has been described by AllMusic as "one of the most successful pop and adult contemporary singers of the '80s and beyond". However, with the combination of MTV and AC radio, adult contemporary appeared harder to define as a genre, with established soft-rock artists of the past still charting pop hits and receiving airplay alongside mainstream radio fare from newer artists at the time.
Output (English): Who did Allmusic refer to as "one of the most successful pop and adult contemporary singers of the '80s and beyond"?