整个括号里是said的宾语从句.宾语从句里面除非是个并列复合句,否则不必把that再重写一遍.比如：
(1) He said,"I am a student and John is my teacher." 改为间接引语后,宾语从句里是个and连接的并列复合句,需要多加一个that:
He said that he was a student and that John was his teacher.
(2) He said,"if I am a student,John will be my teacher." 改为间接引语后,宾语从句里是个带条件状语从句的主从复合句,不多加that:
He said that if he was a student,John would be his teacher.
因此本题中的前两个选项都多写添了that,而C选项一个that也没有,实际上是省略了he之前的那个,那是宾语从句的标志,是可以省略的.所以C正确.