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: Gynaecology & Obstetrics
The most malignant endometrial carcinoma is: 
Select and explain. 
A. Adenocarcinoma, B. Adenoacanthoma, C. Mixed adenosquamous carcinoma, D. Clear cell carcinoma
D: Clear cell carcinoma
Answer: D: Clear cell carcinoma 
Explanation: Endometrial cancers can be histologically classified as