Final answer:
The physician looking out for the interests of other physicians would most likely be represented by a) Medical Association, which works to address the concerns of medical professionals within the broader category of economic interest groups.
Step-by-step explanation:
A physician looking out for the interests of physicians is more likely to be represented by a Medical Association. Interest groups like the American Medical Association work to promote the interests and address the concerns of medical professionals, such as physicians and surgeons. This type of organization falls under the category of professional associations, which are a subset of economic interest groups that also include business groups, labor unions, agricultural groups, and intergovernmental lobbies. These groups are crucial advocates for policy initiatives relevant to their respective members' professions and industries.