A turning point of the continuously high housing price won't app

A turning point of the continuously high housing price won't appear suddenly because there must be a certain process _____ many factors lead to the change.
A、which
B、what
C、where
D、that
【正确答案】：C
【题目解析】：考查定语从句的关系词。此处process作先行词，其在定语从句中作地点状语，故用where。