The manager said that he would seek out methods

题目

The manager said that he would seek out methods
for improving the quality of the product and () we should work harder than before.
A what
B /
C that
D which
请问考神马 选神马 为什么

答案

the manager said……后面是两个并列的从句,两个从句前一个that可以省略,后一个that就不可以省略.
所以选C.