Nerves that only carry impulses away from the central nervous system (cns) are called:

a. motor nerves. b. afferent nerves. c. mixed nerves. d. sensory nerves.

motor Nerves.

Explanation:

These are   bundles of axon  of  the spinal cord located in the CNS. They originated at the  motor cortex of the brain.

They  conduct response signals out of the CNS through the spinal cord to reach the effector(muscles).These signals pass through the brain stem and the spinal cord ipsillaterially, to emerge at the ventral side of the spinal cord to terminate at the skeletal muscles or the smooth muscles.  

The   bundles of  AXON are  called FASICICLES

They are bundle of axons which transduce  signals from the CNS  to peripheral neurons of the muscles of the body.They are different from the motor neuron which have their cell bodies  in the spinal cord and dendrites at the terminal ends.  

However, they communicated with the muscles they innervated through the motor neuron at the terminal.

They have high concentration of neurotransmitter acetylcholine vesicles  for chemical transmission at synapse, and calcium ion in the presynaptic motor nerves   for migration of the vesicles for   increasing the size of end-plate potential