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
Spinnbarkeit refers to? 
Select and explain. 
A. Cervical mucus, B. Uterine gland thickness, C. Cervical os appearance, D. Proliferation of breast alveoli
A: Cervical mucus
Answer: A: Cervical mucus 
Explanation: 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.