Sandy's current consumer surplus for candy is 20. Candy is a normal good for her. When her income increases and the price of candy remains unchanged, her consumer surplus will

The marginal social cost of production is the

A) marginal private cost plus the marginal external cost. B) same as the marginal cost of any externality. C) total cost of any externality. D) marginal private cost minus the marginal external cost.

What are the sources of increasing returns and economies of scale of the recent increase in trend rate productivity experienced in the U.S.?

Please provide the best answer for the statement.