(Always enjoy when that construction is actually valid, people often miss the reflexive part)
"What do you call a student who passed their medical exam with the lowest grade in their year?"
"A doctor"
But note, some schools require a C in prereqs to take further courses. And some schools may put you on academic probation/kick you out if your GPA falls below a C. So D for diploma is a sometimes grade.
These days a 3 is no longer a conceded pass, it's a failure that entitles you to re-attempt your final exam.
