The Sahel is located in Africa. It is the region in Africa that transitions from the Sahara to the Sudanian Savanna. It stretches across in the region from the West of Africa to the East and includes parts of Senegal, Mauritania, Mali, Burkina Faso, Algeria, Niger, Nigeria, Chad, Sudan, South Sudan, Eritrea, CAR, Cameroon, and Ethiopia.
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).
The cardiac cycle is defined as the steps involving the conversion of deoxygenated blood to oxygenated blood in the lungs and pumping it by the heart to the body through the aorta. So i think it would be stable over the years unless u have factors that will affect the cycle depending on a persons health
I think it is c. bodies of water because hydro sounds like hydrate (water)