单选题 When Sanford began reading Professor Matthews" instructions for the essay of the midterm, he was confident that he would get a high grade. Sanford read the five essay topics and decided to spend ten minutes on each. He finished the exam early and used the extra time to reread his essays. After changing a few words, Sanford was confident that he had done well.
Sanford was shocked to discover that he had failed the midterm. He read Professor Matthews" comments and soon understood the reason for his failure. Sanford had not read the instructions properly. Professor Matthews" instructions clearly required a choice of two of the five essays. Therefore, each essay was worth fifty points. Sanford had written briefly about all five essays and had not developed any two of them as fully as he should according to the directions.

A、 We must not write all the topics in an exam
B、 We must be confident in an exam
C、 We must choose two of the essay topics and develop them fully
D、 It is very important and necessary to read the directions carefully