Some products are produced most efficiently when there is a single supplier. what is this called?

Why is it economically necessary for the east germans to build berlin wall

The controlled use of fire by hominids: (a) limited the expansion of hominids into certain environments, such as dry grasslands. (b) decreased the amount of food energy available in the hominid diet. (c) contributed to geographical expansion and food production techniques in positive ways. (d) has been shown to contribute little to the digestive process of hominids.

In the 1600s, the american colonies passed many laws that affected the rights and activities of specific groups of people. which of the following was one of these laws?slaves were defined as servants for apex