What learning process occurs when a dog is exposed to a stimulus that elicits great excitement?

The correct answer is sensitization, which refers to an increased reaction to a stimulus following exposure. When a dog experiences a stimulus that elicits strong excitement, such as the sound of a doorbell or the sight of an arriving visitor, it can become more responsive to that stimulus over time. This heightened state of arousal means that the dog's emotional and physical response becomes greater with continued exposure to the stimulus, demonstrating the process of sensitization.

In contrast, learned irrelevance involves a situation where a stimulus becomes uninformative due to repeated exposure without any significant consequence, which can lead to the dog losing interest in that stimulus. Habituation is characterized by a decrease in response to a stimulus after repeated exposure, and adaptation typically refers to the process where an organism adjusts to changes in its environment to maintain functionality. These processes do not align with the increased reactivity that occurs in sensitization.