Very good!
The prof said the student tried to get lucky (play averages)
by always choosing C and get a 25%.
But, there are 5 possible answers: A B C D E so that should have been 20%.
In fact as the prof says, the correct answer in this test is always either A or B.
A person who knows nothing but reads the instructions should score 50%
by choosing A or B for every question.
