请教feifei-105

105. A survey of alumni of the class of 1960 at Aurora University yielded puzzling results. When asked to indicate their academic rank, half of the respondents reported that they were in the top quarter of the graduating class in 1960.

Which one of the following most helps account for apparent contradiction above?
                    

A.         A disproportionately large number of high ranking alumni responded to the survey.

B.         Few, if any, respondents were mistaken about their class rank.

C.        Not all the alumni who were actually in the top quarter responded to the survey.

D.        Almost all of the alumni who graduated in 1960 responded to the survey.

E.         Academic rank at Aurora University was based on a number of considerations in addition to average grades

答案是A，想请教一下B为什么不对呢？如果有人把名次弄错了，就能够解释上面的现象了啊！

另外，想请问一下这里的A和C怎么解释呢？C我是这样理解的，不是所有真正排在前四分之一的校友回答了这个问卷。这里的respond是指什么啊？到底是指回答问卷了，还是指他选择的是前四分之这个选项啊？