[单选题]
An object slides down a frictionless inclix5 (l. w;kkqnrned plane. At thejc u p*d *y62-aphd0cf bottom, it has a speed of 9.80 m/s. What is the vertical height of c0*h yfa dp du6jpc-*2the plane?
A. $19.6 \; m$
B. $9.80 \; m$
C. $4.90 \; m$
D. $2.45 \; m$
