What marks the edge of a continent?

According to the earth science reference tables, during which geologic time period were the continents of north america,south america, and africa closest together?

Can someone me with this plz? ! i'm putting 20 points on it!

Technology has affected regional settlement patterns in what ways? choose all that apply. climatic improvement strategies have improved crop productivity. mechanized agricultural methods have improved agricultural productivity. participation in the global economy has increased urbanization. population shifts from urban to rural areas has increased as a result of petroleum production. settlement areas have increased as a result of improved water storage and delivery systems.