Question 17 (2 points) In the late 1800s and early 1900s, Standard Oil held a petroleum monopoly in the United States. What two factors allowed Standard Oil to garner over 90% of the market? Significant barriers to enter hindered smaller companies. Predatory pricing drove out other businesses. The Sherman Anti-Trust Act protected Standard Oil's market. Question 18 (2 points) What is the difference between monopoly and an oligopoly. a) In an oligopoly, a good or service is sold by an many large and small companies; in a monopoly, a good or service is sold by a single company. a b) In an oligopoly, a good or service is sold by the government; in a monopoly, a good or service is sold by a single company. c) In an oligopoly, a good or service is sold by a few, large companies; in a monopoly, a good or service is sold by a single company