Over the Past Several Decades, U

Over the past several decades, U.S. firms have faced more competition from overseas firms. Does this have any impact on the market power of U.S. oligopoly firms?

A) No, because domestic firms in oligopoly markets are always so dominant that overseas producers have little or no impact on those markets.
B) No, because the United States government has effectively blocked all imports that might compete with domestic firms in oligopoly industries.
C) Yes, competition from overseas firms can substantially limit domestic firms' market power.
D) There is no way to know.