From the Late 1930s Until the Early 1970s, Courts Tended

From the late 1930s until the early 1970s, courts tended to follow per se rules when deciding antitrust cases.  According to these rules,

A) a firm's control of a large market share was considered intrinsically illegal.
B) the existence of only one or two firms in an industry was not necessarily an antitrust violation.
C) both market share and predatory practices must be considered in determining whether a firm had violated the law.
D) the court should only intervene if the firm charged "unfair" prices.