He worked in a car factory for four years，______ he founded his own company in his hometown．

A．after which B．after when

C．after that D．after it

【答案】A

【解析】

试题分析：这是一个非限制性定语从句，在从句中由于介词after提前了，根据句意，可知要用关系代词which，故选A。