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
A patient with suspected subarachnoid haemorrhage presents with blood isolated in the fourth ventricle on a CT scan. Aneurysmal rupture is likely to have resulted from - 
Select and explain. 
A. Posterior Inferior Cerebellar Artery Aneurysm, B. Anterior Communicating Artery Aneurysm, C. Posterior Communicating Artery Aneurysm, D. Basilar Artery Tip Aneurysm
A: Posterior Inferior Cerebellar Artery Aneurysm
Answer: A: Posterior Inferior Cerebellar Artery Aneurysm 
Explanation: None