There is a common belief among the students in our school they should make great efforts

问题补充：

There is a common belief among the students in our school they should make great efforts to learn and reach the peak of their academic performances.

A. which

B. if

C. that

D. whether

答案：

A. which

B. if

(答案→)C. that

D. whether

解析：根据句意后面从句是对belief的解释说明，从句意思完整，不缺少成分，所以用that引导同位语从句。句意：在我们学校的学生们中有一个共同的信念：那就是他们应该努力去学习并且达到他们学业表现的巅峰。C为正确选项。