Respuesta :
The unconditioned stimulus is the hospital, it is because an unconditioned stimulus is the one responsible of having a response to be activated or for it to be triggered in which in the given scenario, when Ron had seen the hospital, he feels anxious and nauseated where in, this is a response that has been triggered.
The unconditioned stimulus is the hospital.
In classical conditioning, the unconditioned stimulus is one that unconditionally, naturally, and automatically triggers a response. So in this case the hospital triggers the response of anxiety and nausea for Ron.