Answer:
I would expect prices to fall and music production to increase.
Explanation:
Duopoly is a market structure in which there are only two producers. Monopoly, in turn, is a structure in which there is only one producer. In that case, Bieber and Rihana made a cartel, collusion to dominate the market as a monopolist, as a monopolist they can charge a higher price, and produce a smaller amount. By undoing the cartel, both will again compete in price and quantity, so prices tend to fall and the amount of music produced increases.
