[单选题]
Starting from rest, a xm75gmf; ri3w proton 95qidesct ///o( qrfifalls through a potential difference of 1200 V. What speed does 5iqtqcfe /r9s/oi ( d/it acquire?
A. $1.2 \times 10^{5} \; m/s$
B. $2.4 \times 10^{5} \; m/s$
C. $3.6 \times 10^{5} \; m/s$
D. $4.8 \times 10^{5} \; m/s$
