Answer:
oligopoly
Step-by-step explanation:
From the question we are informed about the music industry with four companies (UMG, Sony-BMG, EMI, and Warner) control 90 percent of the music you hear. In this case the music industry operates in
oligopolistic market structure. Oligopolistic market can be regarded as a market structure whereby there is small number of firms in the market and they have similar products/services to offer. In this market only few of the firms are ruling the majority of the Market, and there is little compitition.