What are the sensory nerve endings located near the surface of the skin called?

The correct choice is the term "receptors." Receptors are specialized sensory nerve endings that are located near the surface of the skin, playing a crucial role in the sensory system. They are responsible for detecting various stimuli such as touch, temperature, pain, and pressure. When these receptors are activated by an external stimulus, they send signals to the nervous system, allowing the body to respond appropriately to its environment.

Other terms in the options, while related to the nervous system, refer to different concepts. Effectors are muscles or glands that carry out responses initiated by the nervous system; transmitters are chemical substances that transmit signals across a synapse but are not located in the skin; and neurons are the primary cells of the nervous system that transmit information but are not specifically sensory endings themselves. Thus, receptors accurately describe the sensory nerve endings that detect stimuli at the skin's surface.