i don't think the merchant will let his nephew(---)in the area A.workBto workCbeing work Dworked希望你们也给我讲答案的原因,

i don't think the merchant will let his nephew(---)in the area A.workBto workCbeing work Dworked希望你们也给我讲答案的原因,
i don't think the merchant will let his nephew(---)in the area A.workBto workCbeing work Dworked
希望你们也给我讲答案的原因,

i don't think the merchant will let his nephew(---)in the area A.workBto workCbeing work Dworked希望你们也给我讲答案的原因,
i don't think the merchant will let his nephew(-A--)in the area A.workBto workCbeing work Dworked
let sb do sth 固定用法 让某人做某事
希望能够帮到楼主

let sb. do sth.是固定搭配 选A

A。work
首先看结构，i don't think之后的部分都是think的宾语从句。
然后是短语用法，let sb do sth让某人做某事
其中do用动词原形，故选A