Medical equipment sold to doctors is an instance of ______.

A．a person who sells a great variety of foods
B．an agent who deals with industrial products
C．a person that manages big stores and factories
D．an agent that buys and sells goods in great quantities

A．their products are never sold directly into consumers' hands
B．they usually build their factories far away from markets
C．they usually need agents to sell and deliver their goods into consumers' hands
D．they have used trucks to carry their products to consumers' hands