分类：教育/科学-外语学习
问题：Theyhavestartedaninvestgiation,
A the details of which    B which details the details             D and whose details
回答：A.

后半部分是which引导的定语从句,the details of提前到which.

They have started an investigation.

The details of the investigation are being kept secret.

两句合而为一成为这个句子.

They have started an investigation, the details of which are being kept secret.

他们正在进行一项调查,调查细节没有公布.