The difference between/ʃ/and/ʒ/lies in（）.

A.Ph.D.students’imagination tends to be subverted by their dissertation writing.
B.More time should be saved for Ph.D.students to cultivate their professional skills.
C.With the dissertation shortened and simplified，Ph.D.students can afford more time to hunt for job.
D.By adopting M.L.A.’s suggestion，graduate programs should guarantee academic jobs for all graduates.

A.The idea of designing a shorter program.
B.The completion of a degree in five years.
C.The idea of drafting a shorter dissertation.
D.The suggestions given in the M.L.A.report.