Final answer:
The dorsal roots of a spinal nerve carry sensory information from various body parts via sensory neurons located in the dorsal root ganglia, while the ventral roots carry motor signals from motor neurons in the ventral gray matter, together forming a mixed spinal nerve.
Step-by-step explanation:
The combination of the dorsal and ventral roots to form a spinal nerve plays a crucial role in transmitting sensory and motor information between the spinal cord and the rest of the body. Specifically, the dorsal roots carry only sensory information that originates from sensory receptors located in various body parts like skin and muscle. These sensory axons enter the spinal cord via the dorsal nerve root. The cell bodies of these sensory neurons are situated in structures known as dorsal root ganglia. In contrast, the ventral roots consist exclusively of axons from motor neurons, which project to muscles and are involved in motor signaling. These motor neurons have their cell bodies located in the ventral gray matter of the spinal cord. The spinal nerve itself is composed of both sensory and motor axons as it carries afferent (sensory) and efferent (motor) information. Thus, the correct answer to the question is A) Dorsal roots carry sensory information, while ventral roots carry motor signals, combining to form a spinal nerve.