Regarding sales, someone who has an expertise in a given area or subject, is passionate about the subject, and wants to share that knowledge with others, is known as a/an:

Bob, an employee at machina corp., is well known among his colleagues because of his temper and impatience. during a heated argument with one of his supervisors, he reacts with hostility. bob's manager calls him in for a discussion and listens to what he has to say about the incident, while treating him with dignity and respect. this scenario can be best categorized as one that used