In April 2011, Procter & Gamble and Unilever received fines of 315 million euros by the European Commission for fixing the price of laundry detergent in eight European countries. They admitted to this cartel, which resulted in a 10 percent discount in the fines. The three-year investigation started because of a tip-off by another competitor, Henkel, who was also part of the price-fixing scheme. Henkel received no fine because of its cooperation with investigators. Besides the fines, how did investigators make maintaining this cartel difficult to continue? A) by reminding consumers that laundry detergent has a lot of long-run substitutes

B) by offering a 10 percent discount on the fine if the parties admit to wrongdoing

C) by waiving the fine for just Henkel, which encouraged Henkel to cheat

D) by investigating the cartel for three years so they could prosecute