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
True about endometriosis is/are 
Select and explain. 
A. Endometrial sarcoma is most common, B. Premenstrual spotting absent, C. Most common in 3rd or 4th decade, D. True cyst
C: Most common in 3rd or 4th decade
Answer: C: Most common in 3rd or 4th decade 
Explanation: Most common age group is between 30-45years
Abnormal menstruation seen in 20%
Menorrhagia is seen
If the ovaries are also involved polymenorrhea, epimenorrhagia may be pronounced
Maybe premenstrual spotting seen
Malignancy is rare, commonest being adenocarcinoma