【阅读选择】The ideal battery will store a lot of energy in a small package. Right now, Belcher's model battery, a metallic disk completely built by viruses, looks like a regular watch battery. But inside, its components are very small—so tiny you can only see them with a powerful microscope.
Which of the following is true of Belcher's battery mentioned in paragraph 6?
A.It is made of metal．
B.It is a kind of watch battery．
C.It can only be seen with a microscope．
D.It is a metallic disk with viruses inside it．
正确答案是D