Please Help! I need to turn in this test tonight and it's really COMPLICATED!!! Use the excerpt from Adam Smith’s An Inquiry into the Nature and Causes of the Wealth of Nations to answer the question. Which significant part of the economic system described in the excerpt does Smith omit?

A.
the import of European diseases to the Americas

B.
the import of spices from the East Indies to Europe

C.
the export of Africans as slave labor to the Americas

D.
the export of cash crops from the Americas to Europe

Excerpt from Adam Smith’s An Inquiry into the Nature and Causes of the Wealth of Nations, 1776
The general advantages which Europe, considered as one great country, has derived from the discovery and colonization of America, consist, first, in the increase of its enjoyments; and, secondly, in the augmentation of its industry.

The surplus produce of America, imported into Europe, furnishes the inhabitants of this great continent with a variety of commodities which they could not otherwise have possessed; some for conveniency and use, some for pleasure, and some for ornament, and thereby contributes to increase their enjoyments.

The discovery and colonization of America, it will readily be allowed, have contributed to augment the industry, first, of all the countries which trade to it directly, such as Spain, Portugal, France, and England; and, secondly, of all those which, without trading to it directly, send, through the medium of other countries, goods to it of their own produce. . . . All such countries have evidently gained a more extensive market for their surplus produce, and must consequently have been encouraged to increase its quantity.

The exclusive trade of the mother countries tends to diminish, or, at least, to keep down below what they would otherwise rise to, both the enjoyments and industry of all those nations in general and of the American colonies in particular. It is a dead weight upon the action of one of the great springs which put into motion a great part of the business of mankind. By rendering the colony produce dearer in all other countries, it lessens its consumption, and thereby cramps the industry of the colonies, and both the enjoyments and the industry of all other countries, which both enjoy less when they pay more for what they enjoy and produce less when they get less for what they produce.