Four Companies Dealing in Dairy Products Admitted That They Had

Four companies dealing in dairy products admitted that they had exchanged information to make shoppers pay more for milk and cheese.Two of the companies had increased the price of milk.The other two had passed on sensitive information about prices to their supposed rivals.This is an example of:

A) price fixing.
B) price discrimination.
C) predatory pricing.
D) referral selling.
E) resale price maintenance.