Questions: A well-tested economic theory is often called: a hypothesis. a prototype. a principle. an anomaly.

The answer is: a principle.

Explanation for each option:

1. A hypothesis: This is an initial, testable statement or prediction about a phenomenon. It is not yet well-tested or widely accepted. Hypotheses are the starting points for scientific investigations and need to be tested and validated through experiments and observations.

2. A prototype: This term is generally used in the context of design and engineering, referring to an early sample or model built to test a concept or process. It is not typically used in the context of economic theories.

3. A principle: This is a fundamental truth or proposition that serves as the foundation for a system of belief or behavior or for a chain of reasoning. In economics, a well-tested and widely accepted theory is often referred to as a principle because it has been validated through extensive research and empirical evidence.

4. An anomaly: This refers to something that deviates from what is standard, normal, or expected. In the context of scientific theories, an anomaly is an observation that cannot be explained by the current theory or model. It is not a term used to describe a well-tested theory.

Therefore, the correct answer is "a principle" because it accurately describes a well-tested and widely accepted economic theory.