A professor stood before his class of 20 senior organic biology students, about to hand out the final exam.
"I want to say that it's been a pleasure teaching you this semester. I know you've all worked extremely hard and just about all of you are off to medical school after summer. So that no one gets their GP messed up because they might have been celebrating a bit too much this week, anyone who would like to opt out of the final exam today will receive a "B" for the course." Those that have an "A" or who want to try and get an "A" should stay and take the test. Otherwise your welcome to leave.
There was much rejoicing amongst the class as students got up, passed by the professor to thank him and sign out on his offer. As the last taker left the room, the professor looked out over the handful of remaining students and asked, "Any one else? This is your last chance."
One final student rose up and took the offer.
"I'm glad to see you believe in yourself. It is truly a great pleasure to see people who are willing to make that extra effort, who don't give up, who will always take those extra steps, who always want to better themselves, who always try." Then the professor said, "You all have A's."