Answer: According to the U.S. Department of Justice Merger Guidelines, an Herfindahl-Hirschman Index (HHI) above 2,500 is associated with a highly concentrated industry. If the automobile industry had an HHI of 2,200, then a vertical merger between GM and one of its suppliers would likely be **approved** since the HHI is below the acceptable threshold.
So, the correct choice is: 2,500; approved since the HHI is below the acceptable threshold.
Step-by-step explanation: