A Proton with a Speed of 2 $10^5$ M/s Accelerates Through a Potential Difference and Thereby Increases Its

Multiple Choice

A proton with a speed of 2.0 x $10^5$ m/s accelerates through a potential difference and thereby increases its speed to 4.0 x $10^5$ m/s. Through what magnitude potential difference did the proton accelerate?
(e = 1.60 × 10^-19 C , m_proton = 1.67 × 10^-27 kg)

A) 630 V
B) 210 V
C) 840 V
D) 1000 V
E) 100 V