When a Variable does not have any exponent, what number do you use

Two maps stacked on top of each other. the top map is a map showing the migration of early humans. the map shows a migration path that begins in africa and moves north, east, and south to europe, asia, and australia. another path is shown beginning in northern north america and moving southward through south america. the second map is a map image with the continents and oceans labeled. from left to right the following is shown: the pacific ocean, north america (shaded orange), south america (shaded purple), the atlantic ocean, the southern ocean, africa (shaded green), europe (shaded yellow), asia (shaded blue), the indian ocean, australia (shaded red) and the pacific ocean. antarctica is shown at the bottom of the map. image 1: © 2012 the exploration company, image 2: © 2012 the exploration company according to the map, to which of the following places did humans migrate after reaching north america? north america south america africa europe