If the system's default is to expect the combination of an intelligent student, three hours of instruction, and ~12 hours of hard work a week to produce a C grade or lower in a three-credit course, then the system's broken. Probably the instruction part of it, possibly the grading part.

If the material is difficult, it's the professor's job to teach it in a way that can be understood. If that can't be done in the credit-hours allotted to the class, the class should be worth more credit hours.