Jerry and his housemates each get up around the same time each morning and get ready in the house's two bathrooms.
If someone in one bathroom flushes the toilet, the shower in the other bathroom becomes very hot, causing whoever is in that shower to jump back.
Over time, if Jerry is in the shower, he automatically jumps back if he hears a toilet flush, even before the water temperature changes. In this example,
Jerry initially jumping back because of the hot water is considered a(n)
A. Conditioned stimulus (CS).
B. Unconditioned stimulus (UCS).
C. Conditioned response (CR).
D. Unconditioned response (UCR).