In pavlov’s original studies, the unconditioned stimulus was

In Pavlov's original studies on classical conditioning, he used dogs as the subject of his experiment. The unconditioned stimulus was the bowl of food that he presented to the dog while the unconditioned response was the dog salivated in its excitement to see the food.

This type of galaxy is an approximately ellipsoidal shape and a smooth, nearly featureless image. they are the largest single star systems, in the universe and are built by the collisions of many smaller galaxies.