Looking at differences between a single firm within a perfectly competitive market and a monopoly, which of the following is true?

A: A single firm within a perfectly competitive market, sees the entire downward sloping demand curve of the perfectly competitive market.

B: A single firm within the perfectly competitive market can set its price at any level and will not see a change in the demand.

C: Because it is the only producer in the market, the monopoly sees the entire downward sloping demand curve of the market.

D: Because it is the only producer in the market, the monopoly will sell the same amount, no matter what price it charges.

E: A single firm within a perfectly competitive market must be concerned about the impact of the price effect and the quantity effect.