What Does Thomas Friedman Mean by the Concept of a "Flat

What does Thomas Friedman mean by the concept of a "flat" world?

A) He argues that the world increasingly has social and economic opportunities available to everyone.
B) He argues that it is a one-dimensional world in which the wealthy nations will always have the advantage.
C) He argues that the poor nations will soon "flatten" the wealthy ones and have their own turn as wealthy.
D) He means that we have reached our high point in innovation and discovery and now we must learn to manage ourselves better.
E) None of these statements is correct.