Why Is the Upper Bound of Oligopolies Difficult to Define

Multiple Choice

Why is the upper bound of oligopolies difficult to define?

A) The designation depends on whether firms in these markets are monitoring and reacting to specific rival behavior.
B) The firms must make their moves carefully, knowing that rivals will detect their actions and respond accordingly.
C) The firms in oligopolies are locked in tight competition with only a few other firms.
D) The number of firms in these markets in some cases can be up to 100 or 150.