Three carriers account for 99% of wireless subscriptions in the United States: AT&T, Verizon, and T-Mobile. AT&T's market share in this market is 45%. The cell phone carrier market structure is a form of AT&T's firm demand curve is relatively
a. monopoly; perfect competition; inelastic
b. oligopoly; perfect competition; elastic
c. oligopoly; imperfect competition; inelastic