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
[{'content': 'Unsuccessfulness of DMPA has been primarily because of : \nSelect and explain. \nA. Breakthrough bleeding, B. Effect on lactation, C. Delay in return of feility, D. Failure rate', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Breakthrough bleeding', 'role': 'assistant'}]