<prompt> Magnitude of action potential in neuron, is determined by:NaMg2KCa2  <response>: Ans: A Na Ref: Pal GK. Nerve. In: Textbook of Medical Physiology. Ahuja Publishing House. 2007; 18: 158.Explanation:Depolarization upstroke phase of action potential in a neuron is due to Na influxRepolarization is due to K effluxMg2, Ca2 are not directly involved in generation of action potential in nerve 