Which of the following best describes the relationship between variations and adaptations? A. All variations are adaptations, but not all adaptations come from variations
OB. All adaptations are variations and all variations help organism survive
C. Variations result from adaptations organisms make to the environment
CD. Adaptations result from variations only if they help an organisms survive

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.  

read more on -

maybe because its impossible for balloons to lift a whole entire house.