A well-tested explanation that explains a lot of observations is

A) a hypothesis.

B) an inference.

C) a theory.

D) a controlled experiment.

Well-tested explanation is a declaration that makes something easy to perceive and examination of a set of reality in their relation to one another.

therefore,

A well-tested explanation that explains a lot of observations is called a theory.

hence the right answer is C) a theory

It is C) a theory. So, A well-tested explanation that explains a lot of observations is a theory.