Task: Question Answering
Input (English): Question: A 7-year-old boy presents a subacute picture of cerebellar ataxia and intracranial hypertension. Magnetic resonance imaging demonstrates an expansive lesion in the cerebellar vérmix that captures contrast and obstructs the fourth ventricle. The most likely diagnosis is: 
 Options:  <1> Meningioma <2> Cerebellar metastasis. <3> Glioblastoma multiforme. <4> Medulloblastoma <5> Lymphoma
Output (English): 4