题目内容：
阅读以下文章，回答题：
Antimicrobial resistance has become a global public health issue because
A．new antibiotics are too expensive for poor countries．
B．infections caused by multi—drug resistant bacteria have killed a lot of people．
C．scientists know nothing about multi-drug resistant bacteria．
D．there may be few or no treatment to infections caused by multi-drug resistant bacteria．
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答案解析：