Three systems of two charged particles are shown below. All the particles have the same mass,
 and all are initially at rest. In System X, two positive charges are separated by distance d.
 System Y is similar, but one of the charges is negative. In System Z, both charges are positive,
 but one has twice the charge of the other and the distance between the charges is double that of
 Systems X and Y. When the particles are released, they accelerate until all the electrical
 potential energy is converted to kinetic energy.
 System X-9
 +
 Systemy -
 -
 2d
 System z 9
 +29
 Rank the systems from the one with the greatest final kinetic energy to the one with the least
 final kinetic energy?
 A. X=Z>Y
 B. X>Z>Y
 C. X=Z=Y
 D. X=Y>Z