What effect might the government have on oligopolies? In oligopolies, the government might pts) OA impose barriers to entry with a copyright, which allows only the government to supply a good or service. B. promote competition by allowing large firms to lobby state legislators and members of Congress for favorable laws OC. impose barriers to entry with occupational licensing, where a license is required to provide a good or service. OD. promote competition with a patent, which grants exclusive rights to product a good. OE impose barriers to entry with a free-trade agreement with another country to promote competition.