Which is the primary role of a sensory neuron?

The primary role of a sensory neuron is to transmit signals from sensory organs to the central nervous system (CNS). Sensory neurons are specialized cells that detect stimuli from the environment, such as light, sound, touch, taste, and smell. When these neurons detect a stimulus, they convert it into electrical signals that travel along the nerve fibers to the CNS, where the signals can be processed and interpreted. This function is crucial for allowing organisms to respond appropriately to their surroundings, as it provides the necessary information about external conditions.

The other roles mentioned in the question, such as controlling motor activity, relaying signals, or storing information, pertain to different types of neurons or cells within the nervous system. For instance, motor neurons are involved in controlling muscle movements, while interneurons (sometimes referred to in broader terms as relay neurons) facilitate communication between sensory and motor neurons in the CNS. Additionally, storage of information is a function typically associated with brain structures involved in memory, rather than directly with sensory neurons. Thus, the direct and essential role of sensory neurons lies in their ability to convey information from the senses to the CNS.