Which of the following is true regarding the similarities and differences in monopolistic competition and monopoly ?

• A. the monopolist faces a downward-sloping demand curve while the monopolistic competitor faces an elastic demand curve
• B. the monopolist charges a price above marginal cost while the monopolistic competitor charges a price equal to marginal cost
• C. The monopolist makes economic profits in the long run while the monopolistic competitor makes zero economic profits in the long run
• D. Both the monopolist and the monopolistic competitor operate at the efficient scale