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: Radiology
CT scan shows a suharachnoid haemorrhage following symptoms of sudden headache and paralysis. Next investigation of choice is: 
Select and explain. 
A. 4-vessel angiography, B. SPECT, C. Transacromial Doppler USG, D. MRI
A: 4-vessel angiography
Answer: A: 4-vessel angiography 
Explanation: Ans. 4-vessel angiography