读下面的对话并回答问题。

Joseph: Hello, my name's Joseph. Where are you from?

Andrew: Hi, I'm Andrew. I'm from the U.S. What about you?

Joseph: I'm from the U.K. This is my friend, Gao Ma.

Andrew: Nice to meet you. Where are you from?

Gao Ma: I'm from China. This is my friend, Mary.

Mary: Hello. I'm from Australia.

Andrew: Hello, Mary. Nice to meet you.

1. Where is Andrew from?

    ____________________.

2. Is Joseph from the U.S?

    _____________________.

3. Where's Gao Ma from?

    _____________________.

4. Is Mary from China?

    _____________________.

在一项队列研究中，如果暴露因素较为少见，且又采用历史性队列研究，暴露组应选择（）。

A.一般人群；

B.易回顾人群；

C.特殊暴露人群；

D.有组织的人群；

E.特殊地区人群。