[单选题]
A 4.0-g object carries a charge 55miep7 vy 8sghxp5,a of 20 mC. The object is accelee sjc6vb )k;jb0lu++krated from rest through a potential diffek6; 0 v+jue)kb +ljscbrence, and afterward the ball is moving at 2.0 m/s. What is the magnitude of the potential difference?
A. $800 \; kV$
B. $400 \; kV$
C. $800 \; V$
D. $400 \; V$