Final answer:
The correct statement regarding nerve supply to the skin is c. dorsal root ganglia, which contain the cell bodies of sensory neurons responsible for transmitting sensations from the skin to the CNS. The spinal nerves contain both sensory fibers from the skin and motor fibers to the muscles.
Step-by-step explanation:
Dorsal root ganglia contain the cell bodies of sensory neurons that transmit sensory information from the skin to the central nervous system (CNS). These sensory neurons receive stimuli from the skin and send action potentials through their axons into the CNS via the dorsal nerve roots. On the other hand, motor information is conveyed from the CNS to muscles through axons of motor neurons that emerge from the anterior horn of the spinal cord and pass through the ventral nerve root.
The radial nerve carries not only sensory fibers for cutaneous sensation in the arm but also motor fibers that induce muscle contractions in the arm. Thus, spinal nerves, which include both sensory and motor fibers, provide the nerve supply necessary for the sensory-somatic nervous system to transmit sensory information to the CNS and motor commands back to the muscles.