What character trait reflects a dog's propensity to lose focus on a task?

The character trait that best reflects a dog's propensity to lose focus on a task is distractibility. This trait indicates how easily a dog can be sidetracked or diverted from its current activity by external stimuli or environmental changes. A highly distractible dog may struggle to maintain attention on the task at hand, which is crucial in scenarios such as narcotic detection work, where concentration and focus are paramount.

In contrast, sensory threshold refers to the level of stimulation required for the dog to notice something, agility pertains to a dog's physical abilities and movement, and coercion is related to the use of force or pressure to influence behavior, none of which directly address the issue of maintaining focus during tasks. Therefore, distractibility most accurately characterizes a dog's tendency to become unfocused or inattentive while performing a job.