What would happen if a person sustained damage to their suprachiasmatic nucleus?
They would not be able to fall asleep at night
They would not be able to wake up in the morning
They would not have a circadian rhythm
Their sleep-wake cycle would not be synchronized with the day-night cycle They would develop severe insomnia

Explanation:

An injury to Head/brain can hamper sleep -wake cycle. other than that injuries to other regions can also hamper the sleep-wake cycle, because the pain could be unbearable resulting in loss of sleep. So it is also dependent on kind and severity of the injury.

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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the answer to your question is:

c. complementary base-pairing