An electron and a proton are each accelerated from rest through the same electric potential difference. Which of the following best describes their speeds immediately after the acceleration?
a) Both particles achieve the same speed because they gain the same kinetic energy.
b) The proton attains a greater speed because its larger mass produces a larger acceleration through the potential difference.
c) The electron attains a greater speed because it has a much smaller mass.
d) Both particles experience forces of the same magnitude, so they reach the same final speed.