Answer: B
Explanation:
With the options given, Johnny can only perform worse if he performs worse than his cumulative GPA and also if he performed less than he ever performed before. The last option about Johnny's performing worse than last semester might not necessarily have an effect on his GPA. A cumulative GPA is the total GPA Johnny has gotten since he started school. The last semester might be one of his best semesters and probably had a good result so getting a result slightly lower than his last semester might not necessarily mean there will be a reduction in his cumulative GPA. So option B is correct.