[单选题]
A proton, initially at rest, is accelerated through an elzs 7ain3 77mtwki*pz8scs / ur-)mj ghm.ng84ectric potential difference of 500 V. What is the speed of the proton? n)m.h-g 48csg/urmsj
A. $2.2 \times 10^{5} \; m/s$
B. $3.1 \times 10^{5} \; m/s$
C. $9.6 \times 10^{10} \; m/s$
D. zero
