Definition of Costs in Economics

Costs in economics are defined as opportunity costs, which represent the value of the next best alternative foregone when a decision is made.

Examples

If a business invests in Project A, the opportunity cost is the potential return from Project B, which was not pursued.

Why the Other Options are Incorrect

B. Financial: Financial costs are explicit, but economics considers opportunity costs as broader.

C. Normal Profit: Normal profit is a component of total costs but not the definition of "costs" itself.

D. MES (Minimum Efficient Scale): Refers to the production scale at which average costs are minimized, unrelated to cost definition.

ICWIM Study Guide, Chapter on Economic Principles: Emphasizes opportunity cost as the core definition.

Economic Textbooks: Widely recognize opportunity cost as the key concept in cost theory.

ReferencesThus, the correct answer is A. Opportunity.