In an independent supply chain, the participants collaborate solely on the interactions between the immediate customer and supplier. On the other hand, in a vertical marketing system:

a. firms work together with a common focus on the customer or operation of the supply chain.

b. ownership may overlap, but the emphasis is on working toward common goals and objectives.

c. long-term relationships are more important than gaining a temporary advantage.

d. supply chain members work as a unified system.

e. All of these.