In the 1960s,each Firm in the Computer Industry Was Able

In the 1960s,each firm in the computer industry was able to make extremely large profit margins,some as high as 50 to 60 percent.The margin decreased to 20 to 40 percent in the 1970s and to 10to 20 percent in the 1980s.We conclude that:

A) market power increased in the two decades.
B) the industry evolved from oligopolistic to a more competitive industry in the two decades.
C) lower profit margins were due to the government's regulation to protect consumers.
D) lower profit margins were largely due to the mismanagement of computer firms.