Answer:
Conference/Seminars
Explanation:
Conference/Seminar is a form of social event in which a group of people with similar interest gather in a certain place in order to talk/discuss about a specific issue.
Typically, every conferences/seminars will invited several people as the 'speakers' . These speakers are chosen based on their experience or knowledge in that specific issue.
In the case above, Jack is most likely attending a business conference and the speaker is someone who has a business experience for over 4 years.