Which sentence below best expresses the essential information in the highlighted sentence

in paragraph 4？ Incorrect choices change the meaning in important ways or leave out essential information.

A．There has been much academic corruption involved in the study, but the researchers have no other choice in order to get enough information.

B．Strictly speaking, the study is not academic enough, since one has to do some speculations and consider many factors.

C．The study is not scientific enough, so the results are not reliable, although that is what the researcher can best do.

D．This kind of research should not be purely academic, since this is universal practice in this area of study.