Final answer:
The objective lens of a microscope is the part that is most proximal to the patient, as it is the first lens to collect and focus light from the specimen.
Step-by-step explanation:
The part of the microscope that is most proximal to the patient would be the objective lens. In a typical brightfield microscope, the specimen, or the patient sample, is placed on a glass slide directly above the objective lens. The objective lens is the first lens that collects light from the specimen and focuses it to create an image. This is the lens closest to what is being observed, making it the most proximal to the patient compared to the other parts listed such as the beam splitter, fiberoptics, and binoculars.