Ecologist study the varieties and interactions of

A - living things across time

B-living things across space

C-macromolecules in living systems

D - macromolecules in non-living systems

Ecologist study the variety and interactions of organisms

Human economics and ecology are linked together because human economics utilizes the ecosystem and the natural resources in order for economics to actually exist. As living organisms in the biotic environment, human beings need food, water and resources in order to survive and thus, it is used in trading, buying and selling of the goods, where economics function. It also applies the supply and demand approach and uses strategy in how to maintain and innovate resources.