This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General obstetrics, Subject name: Anatomy
The major contribution of amniotic fluid after 20 weeks of gestation : 
Select and explain. 
A. Ultrafiltrate and maternal plasma, B. Fetal urine, C. Fetal lung fluid, D. Fetal skin
B: Fetal urine
Answer: B: Fetal urine 
Explanation: Origin of amniotic fluid : Early week -Maternal plasma 2 nd trimester - Fetal skin Beyond 20 weeks -Fetal urine Ref: Datta Obs 9e pg 34.