An Oligopolist Differs from a Perfect Competitor in That

An oligopolist differs from a perfect competitor in that

A) there is cutthroat competition in perfect competition but little competition in oligopoly because firms have significant market power.
B) firms in an oligopoly do not produce homogeneous products while firms in perfect competition do.
C) the market demand curve for a perfectly competitive industry is perfectly elastic but it is downward-sloping in an oligopolistic industry.
D) there are no entry barriers in perfect competition but there are entry barriers in oligopoly.