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: Pathology
Vaginal adenocarcinomas in children is caused by- 
Select and explain. 
A. Virus, B. Adminstration of DES to pregnant mothers, C. Hormonal changes, D. All of the above
B: Adminstration of DES to pregnant mothers
Answer: B: Adminstration of DES to pregnant mothers 
Explanation: Adenocarcinoma occurs in young women whose mothers had been treated with diethylstilbestrol (DES) during pregnancy.