A code of ethics governing the behavior of physicians during epidemics did not exist until 1846 when it was ________ by the American Medical Association.
句意： 直到1846年， 关于流行病期间的医生行为道德准则才由美国医药协会颁布。 promulgate颁布。 rescind废除。 presuppose推测。 depreciate贬值。 因此， 本题的正确答案是B。