The Milky Way is a cloud of space dust and debris from planets and stars

This is true to an extent. The Milky Way is a galaxy. A galaxy contains stars, planets, space dust, and some other things. A galaxy is not necessarily, completely made from a cloud of space dust and debris. There are other things that make a galaxy a galaxy.

Explanation:

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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