I have just started M3 year, so take my words with a grain of salt, and please correct me if Im wrong. As far as I know, most students receive Bs, and everyone starts out with a B by default. If you do very poorly, without doing anything seriously unprofessional or not studying or having several unexcused absences, then you will get a C. If you are absolutely OUTSTANDING, then you will get an A.
The vast majority of the students will get Bs as long as they dont stand out in a bad way. However, if Evals are good, then it will really enhance your residency applications.