The correct answer would be C. Between classes, during lunch, and sometimes on the bus.
The passage clearly states that cell phones must be in their lockers or vehicles, so cell phones cannot be used during class. It also states that cell phone use is acceptable if it does not distract others or affect their punctuality.
Lastly, the passage states the cell phone use on the bus is determined by the bus driver, so you would be able to sometimes use your phone on the bus.
