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:

• A. Posterior Communicating Artery Aneurysm
• B. Basilar Artery Tip Aneurysm
• C. Posterior Inferior Cerebellar Artery Aneurysm
• D. Anterior Communicating Artery Aneurysm