Which of the following is not true about a good theory?

A) It uses as few concepts as necessary to explain a phenomenon.
B) It can generate many testable hypotheses.
C) It is never proved or disproved.
D) All experts agree it is correct.

The statement "All experts agree it is correct" is incorrect because scientific theories are constantly being challenged and modified based on new evidence, and there may be disagreements among experts about the validity and accuracy of a theory. It is important for a theory to be able to withstand criticism and testing in order to be considered a good theory.