One major difference between monopoly and perfect competition is that?

• A the perfect competitor is a price taker while the monopolist determines his own output
• B homogeneity of purpose exists for the perfect competitor while non-homogeneity of purpose exist for the monopolist
• C sellers are located all over the world in the perfect competition but sellers are only in one country in the case of the monopolist
• D there is free entry and exist in perfect competition but no free exist in monopoly