According to ivan pavlov’s famous "dog experiments" that eventually were the foundation of classical conditioning as a means of learning, an example of a(an) would be dried meat powder, which causes dogs to salivate when sprayed into their mouths.

Unconditioned stimulus (UCS)

Explanation:

Ivan Pavlov was a Russian scientist, most renowned for his work on conditioned responses. According to Pavlov, there are certain stimuli that naturally trigger certain behavioral responses. For example, the scent or taste of food (referred to as an unconditioned stimulus, or UCS) naturally causes dogs to salivate (referred to as an unconditioned response, or UCR). Pavlov found out that the natural stimulus could be replaced by a neutral stimulus (one that doesn't naturally trigger a response), by associating this stimulus with an UCS.

Pavlov tested this theory with dogs, where he'd offer one of his subjects food, triggering the salivation response, while sounding a whistle at the same time. Over time, dogs came to associate the whistle (the neutral stimulus) with the food (the UCS), and later on, sounding the whistle caused the dogs to salivate even if food was not present - that is, an unconditioned response had become a conditioned response. Pavlov's work was widely renowned, and he is considered an early influence on behavioral theory.

i dont know but thats a great qusestion