First, I want to decide for myself what "community" means on like 41 before looking at the answer choices. The author seems to be talking about the medical community, including doctors and researchers.
Although this community may share ethical values, this is not the basis of their association. The community is first and foremost based on medicine. This is why D is incorrect.
A is a better choice. Before selecting my answer, I want to make sure that I can identify its elements within the passage. This is an important step. What would the common set of problems be? Identifying the most effective treatments for a given illness. What would the shared body of knowledge be? The body of medical research and evidence.
