单项选择题

C
根据下面短文回答下列问题。
Donald was not very good at math. Once they would have a math exam, Donald decided (决定) to sit next to the boy who’s best at math, and copy (抄) down his answers.
The day of the exam (考试) came, and Donald sat next to Brian, who always was at the top (最高的) of the class in math. Donald carefully copied Brian’s answers on to his own exam paper.
After the teacher graded (评分) all the students’ papers, she said, "I wanted to give a prize (奖品) to the student who got the highest grade (分数). But two students — Donald and Brian got the same grade. I’ve thought about it, and have decided to give the prize to Brian."
Donald was angry when he heard this. He stood up and said, "This is not fair (公平)."
"That’s right," the teacher said. "But Brian’s answer to Question 18 was ’I don’t know.’ Yours was ’Neither (也不) do I.’"
The teacher knew it was Donald who cheated because ______.

[A] his answers were the same as Brian’s
B. he got the same wrong answers as Brian
C. he wrote the words "Neither do I"