Walmart's channel members negotiate with one another, buy and sell products, and facilitate the change of ownership between Walmart and its suppliers in the course of moving finished goods from the manufacturer into the hands of Walmart's customers. As products move toward the final consumer, which of the following is true of the channel members within Walmart's marketing channel?

a. They help provide contact efficiency as goods move into the hands of the final consumer.
b. They play roles that are different from those of intermediaries and resellers.
c. They provide division of labor but without any particular specialization in moving goods.
d. They facilitate the change of ownership but not the sale to the final consumer.