A Way That the Ecological Exchange Created by the Addition

A way that the ecological exchange created by the addition of the New World's plants and animals to the Old World's may have contributed to the rise in population was that

A) this exchange made food less expensive and more available to larger numbers of people.
B) new markets were created for food that raised people's incomes around the world and their ability to support large families.
C) complexity and diversity were reintroduced into the human food chain.
D) the exchange promoted urbanization and a healthier lifestyle for people.