Theo gets excited whenever he finds a quarter lying on the ground outside. While walking home from school one day, Theo noticed a shiny round object lying on the sidewalk and became very excited. He soon realized that the object was a bottle cap and his excitement quickly dissipated. Which of the following concepts is demonstrated in this example?

• A. Extinction
• B. Conditioned emotional response
• C. Stimulus generalization
• D. Spontaneous recovery