Which of the Following Is Most Likely to Exert the Bargaining

Which of the following is most likely to exert the bargaining power of a buyer?

A) Barnes and Noble purchases books from publishers for sale in its online stores.
B) Walmart, the world's largest discount store, seeks vendors to supply products made exclusively for its stores.
C) Ground beef producers seek to purchase cattle from ranchers.
D) Cowgirl Creamery, a small cheese producer, seeks a dairy farm for its organic milk supplies.