A tying arrangement exists when
a. a company sells two products that are substitutes for one another.
b. a company requires that a customer tie itself down by signing a long-term purchasing agreement.
c. a buyer is required to buy both a specific product and its complementary product from the same supplier.
d. a company offers discounts to customers if they are willing to buy two different products.
The expert examines tying arrangements for substitutions. The requirements for customers are provided.