This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Angiography, Subject name: Radiology
25 year old male met with an accident and is brought to emergency depament with symptoms of headache and paralysis. CT scan shows sub arachnoid haemorrhage. What is the next investigation of choice? 
Select and explain. 
A. MRI, B. SPECT, C. 4-Vessel angiography, D. Doppler USG
C: 4-Vessel angiography
Answer: C: 4-Vessel angiography 
Explanation: Next IOC in pt. presenting with SAH is 4-Vessel angiograph. To know the cause of SAH IOC - 4-Vessel angiography 2 Veebral aeries & 2 internal carotid ateries. IOC for acute SAH (<48 hrs) - NCCT IOC for chronic SAH (>48 hrs)-MRI