Which of the following best describes the function of afferent nerve cells?

Afferent nerve cells, also known as sensory neurons, play a crucial role in the nervous system by receiving sensory information from the environment and transmitting that information to the central nervous system (CNS) for processing. These neurons are responsible for conveying sensations such as touch, temperature, pain, and proprioception from various parts of the body.

When a stimulus occurs, afferent neurons detect the change and send signals through their axons to the spinal cord and brain, where further processing and interpretation take place. This function is vital for an organism to respond appropriately to its surroundings, allowing for reflexes and conscious awareness of sensory input.

By contrast, the other functions described do not align with the primary role of afferent nerve cells. Transmitting signals to muscles relates more to efferent cells or motor neurons, connecting different nerve cells refers to interneurons, and protection of the central nervous system is generally a function associated with glial cells and the anatomical structures surrounding the CNS.