选择题求助

THAT
分析：
先行词前有形容词最高级修饰的时候不能用WHICH

除此以外
还有：
1)先行词为all, much, little, something, anything, everything, nothing等

2)先行词前有first, last, next, only, very, all, any等词修饰

3)先行词同时含有“人”和“非人”时，用that 不用which，也不用who/whom

that
引导的宾语从句

that
因为the best是最高级，定语从句中最高级后面应该跟that

先行词前有形容词最高级、序数词或only,very,none,no,little,few,much等修饰时定语从句用that引导。
举例：
This is the only reason that I can say.
This is the first step that can be taken.
It is the best one that you may choose.

that
这是定语从句，但因有最高级，故用that好些

在英语中有规定，当先行词被形容词最高级修饰时用that而不用which
所以用that

that