The difference between a firm's total revenue and what must be paid to attract resources from their best alternative use is called

When firms differentiate their products, they

a. provide information to consumers with no additional use of productive resources b. always increase their profits c. always create real differences among products d. frequently create artificial or superficial differences among products, thus raising production costs e. usually strain the physical capacity of their plants

If sellers do not adjust their quantity supplied at all in response to a change in price, the price elasticity of supply is

a. zero, and the supply curve is horizontal. b. zero, and the supply curve is vertical. c. infinity, and the supply curve is horizontal. d. infinity, and the supply curve is vertical.