Which Is a Benefit of Attending a Lecture Given by an Expert

Which is a benefit of attending a lecture given by an expert in a field that you are interested in?

A) The expert will likely write you a recommendation for a job or graduate school.
B) It gives you firsthand practical experience in your field of interest.
C) Listening to a presentation is good practice for a job interview.
D) You get an opportunity to ask the expert any questions you might have.