Which of the following best describes someone who is weary?

The term "weary" most accurately describes a state of being physically or mentally exhausted. When someone is weary, it indicates that they have been exerting themselves, whether through physical activity or mental stress, to the point of fatigue. This condition can lead to a lack of motivation or the need for rest and recuperation.

In the context of the other options, they illustrate states that are contrary to being weary. Feeling energetic after rest suggests a state of invigoration, which is opposite of exhaustion. Being vigorously engaged in activities implies enthusiasm and energy rather than depletion. The idea of being "allergic to fatigue" is not a standard phrase that accurately conveys exhaustion; instead, it suggests a strong aversion to fatigue as if it were an allergen, which does not reflect the actual experience of weariness.

By understanding these nuances, it becomes clear that the correct description of someone who is weary aligns with a profound state of tiredness, both physically and mentally.