Answer: C. resources
Explanation:
Economics can be defined as the fact that how humans make decisions on terms of scarcity of resources. The scarcity refers to the demand for resources like goods and services when they are available in least amounts. Resources like tools, land, labor, raw materials, expertise, and knowledge are chiefly required for the production of goods and services. So, economics can be defined as the study of how people and nations use their resources in situations of limited supply.