A 48-year-old man is brought to the emergency department after sudden loss of consciousness in his backyard. His father reports that he and the patient were having a BBQ at the time, and that he complained of a really bad headache before blacking out. Neurologic examination shows a dilated left pupil with left eyelid ptosis. Non-contrast CT of the head shows hyperdensity in the basal cisterns. Which of the following vessels is the most likely source of bleeding in this patient?
Anterior cerebral artery
Anterior communicating artery
Middle cerebral artery
Posterior cerebral artery
Posterior communicating artery
Anterior communicating artery
Middle cerebral artery
Posterior cerebral artery
Posterior communicating artery
