Is this the reason ________ at the meeting for his being late for six times?

Is this the reason ________ at the meeting for his being late for six times?

A.he explained

B.what he explained

C.how he explained

D.why he explained

答案及解析： A

解析：

此句是省略了关系词的定语从句，因为关系词在定语从句中作explain的宾语。