Which body language indicates a dog is alert?

The correct answer is associated with a dog's mouth being closed, as this can indicate a state of alertness. When a dog is alert, it is often focused and attentive to its surroundings, with its senses heightened. A closed mouth can reflect this vigilant state, as the dog may be concentrating on what is happening around it, rather than being in a relaxed or submissive posture.

In contrast, ears that are drooped suggest a lack of confidence or submission, while a tucked tail often indicates fear or anxiety. Similarly, a lowered body posture is typically a signal of submission or fear rather than alertness. Understanding these body language signals is crucial for interpreting a dog's emotional state and ensuring safe interactions.