When I was in university I took a statistics course. We all had to do a project and a friend chose to answer the question whether choosing "C" or the longest answer, if it was not "C", was most likely to result in choosing the correct. response on multiple choice exams. After analysing a bunch of old exams he delivered statistical proof that this strategy was more likely to give you a right answer than a random choice. I use this strategy on exams when I have absolutely no idea of the answer.