What phrase describes the potential outcome of mistakes on the exam script?

The phrase "may be rubbered out" is correct in describing the potential outcome of mistakes on the exam script because it effectively conveys the idea that errors can be removed or eliminated. The term "rubber" refers to an eraser, a common tool used to correct mistakes in writing. Therefore, when something is "rubbered out," it signifies that it has been erased or written over in order to correct the error.

In contrast, the other options do not align as closely with the notion of correcting mistakes on an exam script. For instance, while "may be hidden" suggests obscuring errors rather than correcting them, "may be highlighted" implies bringing attention to errors rather than eliminating them. "May be erased" could technically suggest a similar action, but it lacks the specific imagery provided by "rubbered out," which is more colloquial and directly related to the act of using an eraser. Thus, "may be rubbered out" effectively encapsulates the action of removing mistakes on an exam script.