(单选题) Which of the following is true? (本题3.0分)

A、 If things are very very small, they are germs.
B、 If things can’t be seen, they must be germs.
C、 Germs are only in dirty water.
D、 Germs are everywhere around us.
出自:佳木斯大学-大学英语Ⅱ(专升本)