In accordance with their merger guidelines, the Justice Department and the Federal Trade Commission would probably challenge a merger if the Group of answer choices number of firms in the industry were very large. industry had a Herfindahl-Hirschman index above 800 and the index rose by 80 points or more. industry had a Herfindahl-Hirschman index above 1,800 and the index rose by 100 points or more. industry had a Herfindahl-Hirschman index below 1,000. firms' markets were very large