Answer:
A. Explains how organisms change in response to the environment.
Explanation:
A scientific theory is an EXPLANATION of an aspect in the natural world. In other words, it just tells why something happens. Now it is not just a guess, it is well-supported by evidence and previous studies.
Now to knock out your other choices:
B. is wrong because:
A scientific theory does not predict. It can serve as a basis for a prediction, or what you call a hypothesis, but it does not predict an outcome.
C. is wrong because:
As mentioned earlier, a theory is WELL-SUPPORTED by evidence and previous research.
D. is wrong because:
A theory does not become a scientific law.