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
Which of the following present similar to unruptured ectopic pregnancy 
Select and explain. 
A. Follicular cyst of ovary, B. Corpus luteum cyst, C. Polycystic ovary disease, D. Ovarian torsion
B: Corpus luteum cyst
Answer: B: Corpus luteum cyst 
Explanation: Halban's classical traid:

Delay in normal period followed by spotting
Unilateral pelvic pain 
Small Tender adnexal mass.

This triad is similar to that seen in classic ectopic pregnancy.