Which synonym is the best substitute for the word perspicacious in this sentence?

Well, since you didn't give the example of the sentence, I am just going to tell you what "perspicacious" means, so that you can choose one of these synonyms which fits best in the sentence you are given. Perspicacious means observant, perceptive, aware, acute, alert, clever, clear-sighted, penetrating, sharp-witted, shrew, savvy ...