Shell and Valero Are Two of the Relatively Few Sellers

Multiple Choice

Shell and Valero are two of the relatively few sellers in the oil-refining industry.Due to the tremendous capital investment required to enter this industry,these companies are insulated significantly from the threat of new competitive entrants and thus have considerable control over price.This market situation is referred to as a(n)

A) cartel.
B) monopoly.
C) natural monopoly.
D) oligopoly.
E) trust.