Voted for Technology.

In broad strokes, technology enables resource extraction surpluses. At a foundational level is agricultural surplus which most societies achieved long ago. Then come other natural resource surplus, and more recently intellectual (or information) extraction surpluses.

It so far doesn't seem possible to jump steps in development. For each phase a society either needs to attain the surplus or have a consort society that provides it. This relationship need not be equitable to work. And often has not been.