main idea. A. Climate conditions in Europe allowed for the introduction of new crops that competed with American foods for popular consumption. B. An important cause of population growth was improved nutrition, due in large part to the addition of the potato and other American foods to the standard European diet. C. Regional landowners developed improved agricultural techniques, and mortality rates declined as governments gained control over traditional plague routes. D. Growth rates varied widely across the continent but were highest in France, Spain, and Britain and lowest in Prussia and the Hapsburg Empire. E. Birth rates went up as more people lived long enough to have their own children, had children earlier, and had larger families. F. Government policies promoting population growth helped to create a large labor force for the manufacturing industry