Ah, the joy of test-writing. Back when my survey sections held 300 students, I used multiple-choice tests. My students would search in vain for a pattern to the key. Frankly, if 7 answers in a row were "C", I'd let it stand. I can't tell you how many Aggies were certain that one of those answers had to be wrong because "No professor would let 'C' be used that much."