This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General physiology, Subject name: Physiology
Presynaptic facilitation is caused by 
Select and explain. 
A. Prolonged opening of calcium channels, B. Prolonged opening of chloride channels, C. Prolonged opening of sodium channels, D. Prolonged closure of potassium channels
A: Prolonged opening of calcium channels
Answer: A: Prolonged opening of calcium channels 
Explanation: Presynaptic facilitation: when a third neuron facilitates the presynaptic neuron at it ternimal end is called presynaptic facilitation It causes increased neurotransmitters by opening ca+ channals Ref:Guyton and Hall textbook of medical physiology 12th edition,page number:675,676,677