Dorsal rami

(a) unite to form plexuses in the cervical, brachial, lumbar, and sacral regions
(b) branch from spinal nerves to innervate muscles of the back
(c) contain cell bodies of sensory neurons
(d) are the structures to which the rami communicantes are attached
(e) are the structures that lead to the sympathetic trunk ganglia

the correct answer is the letter B)

Explanation:

the dorsal ramus of each spinal nerve travels backward, except for the first cervical, the fourth and fifth sacral, and the coccygeal. Dorsal rami divide into medial, intermediate, and lateral branches. The lateral branch supplies innervation to the iliocostalis muscle, as well as the skin lateral to the muscle on the back.

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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this is a good question! i'll do some research and come back when i have the answer!