– Do you know of Guo Mingyi?- Yes. He is an ordinary (普通的) worker helps many poor children

– Do you know of Guo Mingyi?
- Yes. He is an ordinary (普通的) worker helps many poor children in China. We should follow his example.
A. that B. which C. whom

解析：句意：你知道郭明义吗？——是的，在中国他是一个帮助了很多穷苦孩子的普通工人。我们应该以他为榜样。下文中先行词worker为下文定语从句的逻辑主语，指人，故引导词用who或者that，根据所给选项可知选A。

回答的不错