The correct answer is a theory.
A theory is a rational and contemplative kind of generalizing or abstract thinking or the outcomes of such thinking. On the basis of the context, the outcomes might involve generalized illustrations of how nature functions.
A theory can be a source of knowledge that may or may not is related to the specific explanatory models. To theorize is to create the body of knowledge.
Answer:Variation in traits can be caused by variation in protein molecules within individuals' cells. Protein molecules' structures affect their function and the way they connect to other molecules.
Explanation: ^^^ hope it helps :)