A newly diagnosed hypertensive patient is started on prazosin,an alpha adrenergic blocker.Within the hour,he complains of dizziness and loses consciousness.What has happened?

A) The drug activated the baroreceptors, causing an intense parasympathetic discharge, and thereby increasing blood pressure and precipitating a mild stroke.
B) The prazosin decreased his blood pressure too much; the drug-induced hypotension caused the fainting event (syncope).
C) The prazosin caused spasm of the cerebral blood vessels, which, in turn, caused loss of consciousness.
D) The patient experienced a hypertensive crisis.