The answer is A. A law
Step-by-step explanation:
The fact "traits are passed from parents to offspring" has been scientifically proven not only by Mendel but by many other scientists. Additionally, these experiments showed this phenomenon always occurs. In this context, this statement is considered a law, which is a statement that describes an event or phenomenon that always happens and has been proven through experiments. Moreover, this is classified as a law rather than a theory because it only describes a phenomenon of genetics but does not explain it.