A parent has a pile of toys to divide between two children. Assume that there is an even number of each toy. What method of dividing the toys ensures that the final division is efficient?
A) Divide the pile equally
B) Give each toy to the child who cries the loudest
C) Divide the pile so that each child is equally happy
D) Let one child divided the pile into two parts, and the other child decide who gets which part
E) Divide the pile arbitrarily, and then let the children trade toys until there are no more mutually beneficial trades