问题补充：
Is this the reason at the meeting for his carelessness in his work?
A. What he explained
B. how he explained
C. he explained
D. why he explained
答案：
A. What he explained
B. how he explained
(答案→)C. he explained
D. why he explained
解析：考察定语从句。本题中定语从句的先行词是this reason，在定语从句that/which指代先行词作为动词explain的宾语，可以省略。句意：这就是在会议上他解释的关于工作中的粗心的原因吗？根据句意说明C项正确。
