Which Set of Characteristics Best Identifies a Pure Monopoly

Which set of characteristics best identifies a pure monopoly?

A) many firms, homogeneous product, significant barriers to entry, significant nonprice competition, and considerable power over price
B) few firms, differentiated product, no barriers to entry, the absence of nonprice competition, and considerable advertising
C) one firm producing a product with no close substitutes, significant barriers to entry, and considerable power over price
D) many firms, differentiated product, few barriers to entry, and nonprice competition
E) few firms, differentiated product, significant barriers to entry, and significant amounts of nonprice competition