Final answer:
A comprehensive and testable explanation of an aspect of nature that is well-substantiated by a body of evidence is called a scientific theory.
Step-by-step explanation:
A well-substantiated, comprehensive, testable explanation of a particular aspect of nature is called a scientific theory. A theory stands in contrast to a hypothesis, which is a tentative explanation that can be tested by further investigation. When a hypothesis is thoroughly tested and validated by a body of experimental evidence, it may be elevated to the status of a scientific theory. Theories are well-supported and highly reliable explanations that integrate a large amount of information and provide satisfactory explanations for observations and phenomena. Over time, if new data emerge, theories can be refined or expanded to accommodate this new information. Thus, in the context of scientific terminology, the correct answer to the question is C) Theory.