<prompt> A 25-year-old male had severe headache followed by unconsciousness. CSF tap revealed red blood cells. Most likely diagnosis is:Subdural hematomaEmbolismTumourRuptured aneurysm  <response>: Answer is D Ruptured aneurysm: Severe headache, brief period of unconsciousness and blood in C.S.F. is a classical feature of subarachnoid hemorrhage. 