7 In the early 1990s, economists and government officials redefined our nation's annual output from GNP to GDP. The reason for this is that

a.) a product produced and sold in Canada by an American company does little or nothing to promote the economic well-being of any American.

b.) a product produced and sold in Canada by an American company does quite a bit to promote the economic well-being of many Americans.

c.) it is necessary to take depreciation into account in order to arrive at an accurate measure of the nation's net annual output for any given year.

d.) Both (a.) and (c.) above.