This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Sex Hormones, Subject name: Physiology
[{'content': 'Spinnbarkeit refers to? \nSelect and explain. \nA. Cervical mucus, B. Uterine gland thickness, C. Cervical os appearance, D. Proliferation of breast alveoli', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) Cervical mucusRef.-.Ganong25th ed. / 402* The cervical mucus is thinnest at time of ovulation and its elasticity or spinnbarkeit increases such that by mid- cycle one drop can be stretched into a long, thin thread that may be 8-12cm or more in length.* It dries on a slide in an arborizing fern like pattern.* After ovulation it becomes thick and fails to form the fern pattern.', 'role': 'assistant'}]