单选题 The text mainly supplies information for answering which of the following questions?

A、 Can the immune system be affected by emotional factors?
B、 Why can our bodies fight the bacteria and viruses which cause diseases?
C、 How can the immune system be affected by emotional factors?
D、 Why can't blood cells in bereaved people's bodies work properly?

【正确答案】 A

【答案解析】本文通过一些例子证实了情绪会影响免疫系统，是对选项A情绪是否能影响免疫系统的回答。