posted by Nick .
A significant difference between monopoly and perfect competition is that:
A. free entry and exit is possible in a monopolized industry but impossible in a competitive industry.
B. competitive firms control market supply but monopolies do not.
C. the monopolist's demand curve is the industry demand curve while the competitive firm's demand curve is perfectly elastic.
D. profits are driven to zero in a monopolized industry but may be positive in a competitive industry.