This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Unknown
M/c tumour of the ovary - 
Select and explain. 
A. Dermoid, B. Serous epithelial tumor, C. Mucinous, D. metastatic
B: Serous epithelial tumor
Answer: B: Serous epithelial tumor 
Explanation: Ans. is 'b' i.e., Serous epithelial tumorso Most common ovarian tumors is a serous epithelial ovarian tumoro Serous histology accounts for as many as 75% ovarian cancers.CANCER of ovaryClassification of Ovarian CancerOvarian CancerHistogenesisFrequency (%)TypesAge GroupEpithelialCoelomic epithelium85 - 90Serous, mucinous endometrioid, clear cell, Brenner undifferentiatedPeri/postmenopausal (45 + years)Sex cord stromalGonadal stromal5-7Granulosa cell tumor, Sertoli-Leydig tumorReproductive (20 - 40 years)Germ cell tumorsPrimitive germ cells6-7Dysgerminoma, endodermal sinus tumor, embryonal, teratoma, chorio CAPrepubertal-pubertal (15-20 years)OthersMetastatic Krukenberg Types of Epithelial ovarian tumouro Serouso Mucinouso Endometrioido Clear cello Transitional cello Squamous cello Mixed epithelialo Undifferentiatedo Unclassified