All of the following lead to a difference in income EXCEPT

Assume that a manufacturer of new handheld computer makes a sales pitch to a retailer in which he is willing to sell 5,000 at $10, 7,000 for $8, 9,000 for $7

But any orders above that amount will start costing the retailer more money on a per-unit basis. The president of the retailer asks why he can't get a discount if he orders more. Can you provide an answer that would help this president understand this apparent paradox?

Research suggests that the relatively higher rate of growth of output per capita between in China between 1996 and 2011 was the result of which of the following?

A) an increase in the rate of technological progress B) an increase in K/NA C) an increase in the rate of growth of N D) an increase in the saving rate E) both A and D