<prompt> The ion that contributes maximally to the development of RMP is:NaKCl-Ca  <response>: A resting cell is much more permeable to K as compared to Na or other ions. During resting conditions, if all the ions are moving down their concentration gradients to finally reach equilibrium, the movement of K will be much greater. Thus, K diffusing out, down its concentration gradient will be the greatest contributor to the RMP. As K diffuses outward to reach equilibrium, it drags the membrane potential to its own equilibrium potential. Equilibrium potential for K - 90 mV 