Final answer:
The term applicable to chiropractic that excludes spiritual or supernatural explanations and relies on scientific methods is (D) Naturalism.
Step-by-step explanation:
The term that applies to chiropractic using science, rather than spiritual or supernatural means, to study and explain natural phenomena is naturalism. Naturalism is an approach that explains all phenomena, including religious experiences, in terms of natural forces without recourse to supernatural elements.
It seeks to account for all reality and experiences in terms of physical processes and adheres to the methods of gaining knowledge that rely on evidence and logic. In contrast, the other options represent different philosophical views: A. Rationalism emphasizes reason as the source of knowledge, B. Vitalism involves a belief in a life force beyond the biochemical, and C. Holism is an approach that looks at systems as wholes that are more than the sum of their parts.