This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Contraceptives, Subject name: Gynaecology & Obstetrics
[{'content': "The Hormone which forms the basis for 'Basal Body Temperature' as a method of detecting ovulation is : \nSelect and explain. \nA. Estrogen, B. Progesterone, C. HCG, D. Oxytocin", 'role': 'user'}, {'content': "Answer: B \nExplanation: This Method is based on the fact that after ovulation, progesterone level in the blood increases Progesterones have a Thermogenic effect, increasing the basal metabolic rate and causing the rise of temperature by 0.5degF the luteal phase. Day of 'temperature shift' indicates the time of ovulation.", 'role': 'assistant'}]