Answer:
sprinting fast around the school track
Explanation:
The question is asking for a "vigorous" workout. The word "vigorous" is a context clue that means the answer should include something challenging or fast or having a high-intensity.
Among the choices mentioned, it is only "sprinting fast around the school track" that is vigorous because this exercise helps increase your heart rate. All the other choices such as walking casually, floating in the pool or stretching are low-intensity exercises.
