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
Maternal sources account for what percentage of fetal thyroxine at term 
Select and explain. 
A. 10%, B. 30%, C. 50%, D. 70%
B: 30%
Answer: B: 30% 
Explanation: 30% of fetal thyroxine at term is derived from mother.