For which of the following reasons can it be inferred from the passage that universities are trying to change grading standards?

参考解析：

推理判断题。根据原文最后一段第二句“A teacher who gives high grades for ordinary achievement, or passing grades for less than acceptable results quickly ends up with mostly uninspired and unmotivated students”可知，如果一个老师总是关注奖励，或者对表现一般的学生也给予高分，那么他的学生最终都会不思进取，不求上进。而该段的最后一句 “In this connection, it is interesting to note the growing efforts at colleges and universities to tighten grading standards and restore failing grades”又指出，有趣的是注意到各学院和大学越来越努力地收紧评分标准和恢复不及格成绩。因此，一些大学严格评分标准的原因是解决针对一些老师对表现一般的学生也给以予高分这一问题。故选C。