Which of the following was the union's main strategy during the civil war

Me with this psychology homework, i’m struggling with it.

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.

After about 1000 b. c, some people in siberia meaning their lives wre bassed on herding animals. a. pastoral b. collective c. irrigate d. dalits