What term refers to a thing or event that causes a response in an individual or system?

The correct term for a thing or event that causes a response in an individual or system is "stimulus." In a psychological or physiological context, a stimulus is anything that can provoke a reaction or response, whether it be a sensory input such as light, sound, or temperature, or an event that prompts an action in an organism.

In the context of behavioral science and retail, understanding stimuli is crucial because they can influence consumer behavior and decision-making processes. For example, visual merchandising in stores often uses stimuli like attractive displays and promotional signs to elicit a purchasing response from customers.

The other terms provided have different meanings. "Response" refers to the reaction itself following a stimulus. "Feedback" generally involves information returned from a system or process regarding its output, which isn’t directly the trigger but rather an evaluation of the outcome. "Cue" could refer to a signal used to trigger an action but in a less direct manner than a stimulus, which explicitly causes a reaction. Thus, "stimulus" is the most accurate term for something that initiates a response.