Which statement correctly describes sensory and motor neurons?

• A. Sensory neurons transmit signals from the brain to muscles; motor neurons receive external stimuli.
• B. Sensory neurons receive external stimuli and pass signals to the CNS; motor neurons carry signals from the CNS to muscles or glands.
• C. Both types carry signals from the CNS to effectors only.
• D. Neurons do not transmit signals; only glial cells do.

Answer: (B)

The key idea here is how the two main neuron types move information. Sensory neurons (afferent) detect stimuli from the body or environment and send impulses toward the central nervous system for processing. Motor neurons (efferent) take impulses from the CNS out to muscles or glands to produce a response, like a muscle contracting or a gland secreting. This makes the statement correct because it accurately assigns external-stimulus detection and transmission toward the CNS to sensory neurons, and the transmission from the CNS to effectors to yield action to motor neurons. The other descriptions mix up the direction of signaling or imply neurons don’t transmit signals, which doesn’t fit how the nervous system communicates.