Which is the main type of chemical messengers secreted by the male gonads?

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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i think the answer would be d

i do believe the correct answer would be the third one. location c, because earth is tilted away from the sun at this time

hope this