Oligopolists Prefer to Compete Through Advertising and Product Differentiation Because

Oligopolists prefer to compete through advertising and product differentiation because

A) the greater the degree of product differentiation in the mind of the consumer, the greater the degree of interdependence among rivals.
B) price wars are illegal according to existing antitrust statutes.
C) advertising and product development enable them to realize greater profits without increasing market share.
D) rivals may find it easier to respond to a price decrease than a style change or advertising campaign.
E) it doesn't pay to raise price when the demand curve is highly price inelastic.