At a college fair, the best person with whom to discuss a college that you are interested in is the admissions representative, the admissions representative is the best person to go to because they have all the information and knowledge of college admissions, especially the criteria set to attend the school. Therefore, the rep would be able to guide you in a more efficient manner than any other professionals in the answer choice.
It's the only answer thats a place with official jobs. A normal farm would be there too, but a backyard farm is someones hobby and not a paying occupation, so OSHA isn't in charge of that.