Whether a flame or not, here is the proper response: Thank them for their valuable input, this will help you realize early on why you may have problems in interviews, etc. You have a few years to fix this issue, work on it.
There are plenty of people who like to participate in class and do so without coming off as gunners. To be a gunner, not only do you have to participate a lot, but you have to do so with an irritating attitude that you are above everyone else.