Three boxes A, B and C lie along a straight line on a horizontal frictionless surface, as shown. Box A is initially moving to the right with speed v while the other two boxes are initially at rest. If all collisions are elastic, and the masses of the boxes can be chosen freely, which of the following is closest to the maximum possible final speed of box \mathrm{C} ?
Answer Choices
A. v
B. 2 v
C. 3 v
D. 4 v
E. 5 v
