The principal animal was the jaguar.
Improved technology allows to create more goods and to increase the efficiency of providing services (answer d.) and this is they way that it increases standards of living. If there are more goods and services then more people have an access to them.
Answer:
The earliest civilizations to develop were all situated near major rivers. These rivers provided a regular water supply and a means of transportation. The animals that flocked to the rivers to drink were a source of food... Thus they were able to produce enough food to support increasingly large populations.
Hope that helps?
I think the answer would be executive power.
