The Idea of the "Six Degrees of Separation" Refers to What

The idea of the "Six Degrees of Separation" refers to what?

A) The idea that there is little separation between illegal businesses and socially responsible ones.
B) The theory that states don't cooperate against crime because sovereignty separates them.
C) The idea that a relatively small number of actors connects producers and consumers in illicit markets.
D) The belief that animal trafficking will lead to the extinction of some animal species in a short amount of time.