Every year,millions of people visit Hangzhou,

网友回答

D.known
定语从句省略了“which is”
完整的句子其实就是Every year,millions of people visit Hangzhou,which is known for the West Lake.
======以下答案可供参考======
供参考答案1:
D.known
供参考答案2:
选D 非限制性定语从句省略了which is