[单选题]
A ball is thrown downward from the top of a buildind* (n7 1ethogwe1jv92 bmt.m rg with an in; a ukk0gnoz)4itial speed of 25 m/s.04gzn;ao) kku It strikes the ground after 2.0 s. How high is the building?
A. $20 \; m$
B. $30 \; m$
C. $50 \; m$
D. $70 \; m$