Whichofthefollowingchoicesisnotcorrect？

Whichofthefollowingchoicesisnotcorrect？
A.Tocontrastmeanstoshowthedifferences
B.Itisnecessarytohaveatopicsentenceinyouressay.
C.ThePoint-by-pointapproachisbetterthantheSubject-by-subjectapproach.
D.Tocomparemeanstoshowthesimilarities
正确答案：ThePoint-by-pointapproachisbetterthantheSubject-by-subjectapproach.