When Taco Bell Requires Its Franchisees to Purchase All Their

When Taco Bell requires its franchisees to purchase all their raw materials and supplies from the franchisor in order for the franchisor to maintain quality control,it is:

A) engaging in an illegal exclusive distribution agreement.
B) enforcing an illegal tying agreement.
C) employing a dual distribution agreement.
D) violating the franchisee's right to fair trade.
E) enforcing a tying agreement, which courts generally consider legal as long as there is sufficient proof that these arrangements are necessary to maintain quality control.