[单选题]
Ball A is dropped from the top of / :t9 uqa n:4kqzgosibb(+s( a;wtrc9a builtjv, p8hx 6gka )r(yau 3gp)ll(y*,cl ding. One second later, ball B is dropped fromxvy a)*,y8 ,j 3tcr6)(akgul hl(p lgp the same building. As time progresses, the difference in their speeds
A. increases.
B. remains constant.
C. decreases.
D. cannot be determined from the information given.
