The plasma membrane is much more permeable to k+ than to na+. why? a. the na+-k+ pumps transport more k+ into cells than na+ out of cells. b. ligand-gated cation channels favor a greater influx of na+ than k+. c. there are many more voltage-gated k+ channels than voltage-gated na+ channels. d. there are many more k+ leak channels than na+ leak channels in the plasma membrane.