These are literally the only options on the table (because I'm not going to choose the hidden third option, "forget to do your homework"). I'm not really seeking advice for small-fry personal problems as much as presenting a philosophical question: What would you do in this situation? Would you avoid conflict even if it means criticizing someone without giving her a chance to offer a rebuttal? So have fun.
As for the 0.01% chance that the individual in question somehow locates this topic, congratulations on being the subject of an exceedingly random topic in an obscure Internet message board.
"Offend the recipient" is a pseudonym for "you're always late" and "you didn't do much of nothin' last month", though expressed in a marginally more diplomatic way. Now you know.