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
The first investigation of choice in a patient with suspected subarachnoid haemorrhage should be - 
Select and explain. 
A. Non-contrast computed tomography, B. CSF examination, C. Magnetic resonance imaging (MRI), D. Contrast-enhanced computed tomography
A: Non-contrast computed tomography
Answer: A: Non-contrast computed tomography 
Explanation: Investigation of choice for acute SAH is non-contrast CT scan.