<prompt> Vngiogram of basilar artery bifurcation showingBrain TumorA-V malformationAneurysmAtherosclerotic block  <response>: C Aneurysm Two-dimensional angiogram showing the aneurysm arising from the basilar bifurcation arrow. Three-dimensional angiogram of the same blood vessels, showing the aneurysm red arrow and surrounding blood vessels in greater detail. 