[单选题]
Ball A is dropped frh apxk+w z(3pduw e7.vdy(l,+r; e5qpl6k b)mom the top of a building. One second later, ball B is dropped from the same building. As time 6mrql)5kbe;p progresses, the distance between them
A. increases.
B. remains constant.
C. decreases.
D. cannot be determined from the information given.