Final answer:
The characteristic not key to functional medicine is the Use of herbal supplements. Functional medicine is based on evidence-based treatments, focusing on the root cause of disease and considering the patient's entire system.
Step-by-step explanation:
The key characteristic of functional medicine not included in the options provided is B) Use of herbal supplements. Functional medicine emphasizes a systems-oriented approach that focuses on identifying and addressing the root causes of disease. It incorporates a detailed understanding of each patient's genetic, biochemical, and lifestyle factors and leverages that data to direct personalized treatment plans. While functional medicine practitioners might use herbal supplements, it is not a defining feature like the focus on the root cause of dysfunction, use of evidence-based treatment, and consideration of a patient as a whole system.
By contrast, traditional Chinese medicine often relies on a range of natural substances, such as cicada shells and ginseng, and may be part of a broader ethnomedical system. In this system, healers act similarly to pharmacists, creating various forms of medications from these substances. The choice of treatment, whether traditional Chinese medicine or biomedicine, typically lies with the patient, indicating a complementary medical system rather than a strictly functional approach.