（6分13秒-7分21秒）When Bill Gates mentions that “What are the key pieces？First， we need strong health systems in poor countries.That'；s where mothers can give birth safely，kids can get all their vaccines.But， also where we'；ll see the outbreak very early on.We need a medical reserve corps”.Here “medical reserve corps”refers to

A.lots ofmedical internswho'；ve got the training and backgroundwho are ready to go， with the expertise.

B.lots of top doctors in this fieldwho'；ve got the training and backgroundwho are ready to go， with the expertise.

C.lots of people who'；ve got the training and license who are ready to go， with the expertise.

D.lots of people who'；ve got the training and backgroundwho are ready to go， with the expertise.

正确答案：lots of people who'；ve got the training and backgroundwho are ready to go， with the expertise.