If Mr. Riviera did not need a pacemaker installed and did not have any other surgeries over the course of the next year, which plan would be cheapest, and
how much money would he save per year on the cheaper plan over the more
expensive plan?

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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by drinking easy

very easy

the answer is:

carbon dioxide