The Ungrateful Ones

Pretend you're in this kind of situation:
you're in class, doing an extra hard seatwork that would really make your brain shrink and dry and shrivel up, and its obvious that the persons around you are also having a difficult time figuring out how to solve the given problem. Then suddenly, inspiration hits you and you start solving the problem in the most logical way--for you--until you come up with an answer. Eureka!! You solved it! You got an answer! But you start rechecking your work in case there was something wrong with it. Hmm, seems ok to you. Then the person beside you, who obviously noticed your sudden enthusiasm to the killer-problem, leans over and peers at your notes and looks at you with big puppy-dog-can-I-borrow-your-notes? a.k.a Can-I-copy-your-answer? Expression. Being the ever generous person, you happily lend your notes to that person with matching explanation of how you arrived at such a certain answer. That person listens, copies your work then smiles afterwards, happy that she, too, finally had an answer.
the time for the checking has arrived. You're somewhat confident of your work so you just sit back as you watch your teacher solve the problem on the board. Unfortunately, something absolutely wrong happened. Dreadfully, you watch your teacher encircle an answer much more different than yours and you belatedly realize that your solution was the wrong solution. Normally, at this time, you start talking to yourself, muttering things about why should you study this thing when you just absolutely hate it and stuff. Then as you tried stopping your hand from placing a big X-mark on your paper, the person beside you, the one who copied your notes, turns to you and looks at you warily. Without even a hint of gratefulness, she tells you in a deadpan voice that you were wrong in solving the problem that's why she had a low score for the seatwork. Ok, you try looking guilty and sympathetic and sorry when deep inside you want to hack her head off!!
so here are your choices in terms of how would you react given the situation above:
A.) you apologize, say your a real klutz in physics anyway and just bite your tongue and take out all your anger to your overstuffed, overly large teddy bear who only had one eye left due to all the punches and kicks you have bestowed on it.
B.) no comment, no reaction. Its not your fault, really. And its just better if you give her the cold shoulder. At least no one gets hurt physically....Right?
C.)follow the statement above: hack her head off!! the nerve of that b****!! You already helped her and she thanks you by blaming you of letting her get a low mark!?
I don't really understand why some people are like the person-who's-beside-you. I mean, hello? You already gave something to them and they return your generosity by shoving to your face that you're really stupid and how could you think of a solution like that when its completely off the wall!? they are so immature and stupid and childish and most of all, UNGRATEFUL!! people who're like this should be persecuted and sent to the guillotine!! Down with them!! Eliminate them from the face of the earth!! Those scumbags!!

(Note to reader: If ever the situation above happens to you, the best way to avoid this problem is to feign ignorance and lie through your teeth that you absolutely have no idea how to solve the problem and why don't she just mind her own business and use her brain for once in her life.)