[单选题]
A proton, initially at res txcsdb0-h u( d8hz0vo952f2mfzdi2u t, is accelerated thrai0 ua(q dgd9b 77l .bem:wsv*ough an electric potential difference of 500 V. What is the speed of the pro gi7us9*em(d b:aw7b0.qvd alton?
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
