Satellites help map the bottom of the ocean floor that we ourselves can not reach.
Mountain chains and river systems generally run North-South throughout the continent thus making for formidable barriers to East-West expansion.
Coal, oil, natural gas, minerals
C
Given that the World population changed little between this time, we can gather than the birth and death rates were similar, since they seem to cancel each other out from 1200-1400. To clarify, think of this. If you add something to a total (think births to population), but take away the same number (think deaths from population) you end up with the same total as before. Because of this, A is the correct answer choice (The birth rate and death rate were about equal).
<span>Hemisphere is a half of a sphere.</span>
