The correct answer is: response.
One of the characteristics of the living organisms is their ability to respond to a stimulus. This is the way to react on the change in the environment. Stimulus first needs to be detected via receptors (light, sound, touch etc). Receptors convert the stimulus into electrical signal. Coordination of different signals from receptors involves processing all the information so that the body can produce an adequate response. Effectors are organs that perform the response (muscles, gland).
