As Part of GGG's Garden Gnome Marketing Strategy, It Requires

As part of GGG's garden gnome marketing strategy, it requires its distributors to purchase a garden gnome pedestal with each gnome. The distributors don't have to sell each gnome with a pedestal, however. The distributors argue that this constitutes an illegal tying agreement. Which of the following is NOT a factor in determining if a tying agreement violated antitrust laws?

A) Whether the tying and tied products are two separate products.
B) Whether the products are reasonably interchangeable with other products in the market.
C) Whether the seller posses sufficient economic power in the tying market to be able to restrain competition in the tying market.
D) Whether the arrangement involves a "not insubstantial" amount of interstate commerce.