An immunologist, osteoimmunologist, or allergist who has completed medical school cannot practice medicine until he or she passes the

After medical school, a physician must pass the United States Medical Licensing Examination (USMLE) to obtain a medical license and practice medicine. The MCAT is taken to apply to medical school, while the PCAT and SAT are not physician licensing exams. Therefore, the correct choice is A, USMLE.

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