<s>[INST] context: An ependymoma is a glial tumor of the ependymal cells that line the center of the spinal cord and the ventricles of the brain. There are several different types of ependymoma cancers, which are also classified by grade. The three grades used for ependymoma cancers are determined by how closely the cancer cells resemble normal cells. The lower the grade, the more closely the cancer cells resemble normal cells. The different types of ependymomas appear in different locations within the spinal column or brain. Grade I tumors - These include subependymomas and myxopapillary ependymomas, and are typically slow growing. Myxopapillary ependymomas tend to appear at the lower end of the spinal column. Subependymomas appear near a ventricle in the brain. These ventricles are involved in the creation of cerebrospinal fluid. Grade II tumors - These are the most common ependymomas. Many ependymoma subtypes exist in this grade, including cellular, papillary, tancytic, RELA fusion-positive, and clear cell ependymomas. These may appear anywhere along the ventricular system where cerebrospinal fluid is produced. Grade III tumors - These are known as anaplastic ependymomas and are typically faster growing than the other grades. Anaplastic ependymomas are usually found in the skull, brain, and brain stem. They are rarely found in the spinal cord. Refer robbins 9/e 1334 [/INST] question: Rosette shaped arrangement of cells is seen in | options: A: Thecoma of ovary B: Ependymoma C: Neurofibroma D: Lymphoma | answer: B </s>