Which of the following malignancy is MOST sensitive to radiotherapy?

Dysgerminomas are usually unilateral and are the most common type of germ cell tumor seen in patients with gonadal dysgenesis. They are highly radiosensitive and chemosensitive. Serous cystadenoma is the most common epithelial cell neoplasm. 70% of these tumors are benign and surgery is the treatment of choice. Mucinous cystadenoma is the second most common epithelial cell tumor of the ovary. Surgery is the treatment of choice. Cystic teratoma: comprise approximately 10 to 25 percent of all ovarian neoplasms and 60 percent of all benign ovarian neoplasms. Surgical excision is the treatment of choice. Ref: Obstetrics and Gynecology By Charles R. B. Beckmann page 443.