I would forget bulk. You have the rest of your life to eat bulk food. On this occasion I suggest brain food:
Mixed nuts, fish, broccoli, bananas, pomegranate and/or cranberry juice.
And no added fats, such as deep fried breading or starches, potatoes, cheese, white rice, non-multigrain bread or vegetable oils. Foods such as these could, however slightly, diminish a clear mind... the kind needed to pass your exams with every scrap of advantage you can give it!
And good luck to you!