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: Physiology
Rate limiting step in cholinergic transmission ? 
Select and explain. 
A. Synthesis of acetylcholine from choline, B. Active uptake of choline in axons, C. Active uptake of acetylcholine by synaptic vesicle, D. Release of acetylcholine from synaptic vesicle
B: Active uptake of choline in axons
Answer: B: Active uptake of choline in axons 
Explanation: Ans. is'b'i.e., Active uptake of choline in axonsAcetylcholine synthesis and releaseCholine is actively taken up by the axonal membrane by Na*; choline cotranspoer. (Rate limiting step). This step is blocked by Hemicholinium.