[单选题]
A ball is thrown downward fro y2:c: 3m*mf(+a*zthohy gja pm the top of a b/ qrt5+ )eyhhluilding with an initial speed of 25 m/s. It striyeqh 5)r/ +htlkes the ground after 2.0 s. How high is the building?
A. $20 \; m$
B. $30 \; m$
C. $50 \; m$
D. $70 \; m$
