The tendency of organizations to become increasingly dominated by small groups of people.

The correct answer is the iron law of oligarchy.

The iron law of oligarchy was phrase coined by the sociologist, Robert Michels. By the ' iron law of oligarchy', Michels meant that all organizations, despite the democracy when they first formed, will eventually become oligarchies (where the power is held by a small group of elites). 

It's most likely choice a, it makes the most sense in my opinion.

Yes you are cute answer theories to explain the colonization of the new world the last great habitable landmass to be occupied by humans focus on the bering land bridge, or beringia, which emerge by siberia and alaska the last ice age.