People in different countries are different in what they eat and ___ they cook their food.

首先what they eat and the way they cook their food 这部分作为different in中in 的介词宾语。what they eat 和 the way they cook their food 相互间是并列句，and是用来连接这两个并列句的。what they eat 可以忽略不看，他是完整的并列从句中的一句完整句。

假设用你选定的B，填入句中，... different in the way in that they cook their food. in that 能充当从句中的什么角色呢？ 从句动词cook的宾语已经有了，是their food, in that的that也是宾语，和their food重复了，冲突了，所以不能用B.

A 意思不符
B.in 是介词,介词后必须用which
C.缺in 或把which 去掉
D.正确应是the waythat,在此句中that做宾语,可省略

我先讲WAY的句型

the way(定语从句) 1 ---that引导2----in which引导3-----不用引导句
(the way 的定语从句只有这些形式!)

D项定语从句省THAT 正确
B要该成the way in which
C要该成the way in which

嘻~~给我加分