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
How is iodide transported across the placenta 
Select and explain. 
A. Simple diffusion, B. Carrier - mediated process, C. Endocytosis, D. No transport
B: Carrier - mediated process
Answer: B: Carrier - mediated process 
Explanation: Iodide is transported by a carrier mediated process and is energy - requiring active process. Placenta indeed concentrates iodide.