Which of the following is a sign of an anxious horse?

Pacing is considered a clear sign of an anxious horse as it typically indicates restlessness and an inability to relax. When a horse is anxious, it may exhibit behaviors such as consistently moving back and forth or circling in a confined space, which is a physical manifestation of their stress and discomfort. This behavior often signals that the horse is trying to cope with its anxiety, suggesting a need for a more conducive environment or intervention to alleviate its distress.

In contrast, signs such as laziness, a calm demeanor, and focused attention do not align with typical anxious behavior. A lazy horse may simply be uninterested or fatigued rather than anxious, while a calm demeanor usually indicates that the horse is relaxed and not experiencing stress. Focused attention can sometimes mean the horse is alert or engaged, but it does not inherently imply anxiety unless accompanied by other signs of distress. Thus, pacing is the most definitive indicator of anxiety in horses among the options presented.