This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
An elderly, hypeensive patient presented with sudden onset headache, vomiting, neck rigidity without focal neurological deficit. Diagnosis: 
Select and explain. 
A. Subarachnoid hemorrhage, B. Ischemic stroke, C. Subdural hemorrhage, D. Meningitis
A: Subarachnoid hemorrhage
Answer: A: Subarachnoid hemorrhage 
Explanation: Ans. a. Subarachnoid hemorrhage (Ref Harrison l9/e p1784, I8/e p2262-2263; Sobiston I9/e p1880-1882; Schwaz 9/e p1534-1536; Bailey 25/e p304)An elderly, hypeensive patient presented with sudden onset headache, vomiting, neck rigidity without focal neurological deficit, diagnosis in this case is subarachnoid hemorrhage.