Country A's steel industry files a dumping complaint with Country A's Department of Commerce. The complaint alleges that the largest steel firm in Country B, in Country C, and in Country D are dumping steel in Country A. In the investigation, the price of a ton of steel in each country was found to be Country A $700 Country B $940 Country C $630 Country D $860 a. Which steel firms will be found to be dumping? Briefly explain. b. For each steel firm that is dumping, compute the dumping margin