Answer:
The correct answer is A. Skillful.
Step-by-step explanation:
The word "dexterous" is an adjective whose meaning implies that a person has, with respect to a certain topic, not only a complete and punctual knowledge, but also a vast experience in the handling of said knowledge, and the ability to apply said knowledge and said experience through mechanisms of action that allow to master the question without major difficulties. In short, the person who has absolute control over some subject or question is dexterous.