Which of the following behaviors indicates enthusiasm and determination in K9 searches?

The behavior that indicates enthusiasm and determination in K9 searches is characterized by intensity. Intensity in a K9's search process reflects a high level of energy and eagerness to find the target scent. When a K9 exhibits intense behavior, it demonstrates a strong motivation to locate the specific odor, often displayed through heightened alertness, increased speed, and a persistent drive to follow the scent trail.

This enthusiasm is vital during searches, as it can lead to more effective and efficient results. An intense dog is likely to put in extra effort during the search, which can be crucial in various scenarios, such as locating narcotics or tracking a suspect. Therefore, intensity is a key indicator of both the K9's engagement and effectiveness in their search tasks.