vigilant, wide awake, aware, watchful, attentive, observant, circumspect, wary, chary, heedful, canny
Thinking about Grendel, I think 'A' is most likely.
The following sentence is calling for: B. Active listening. As a general rule you don't skip review for a big test that could dramatically sway your grade in either a positive or negative direction and course. I hope that answers your question.
your energetic dog is the correct answer