Colonial era: british
WW1: American
WW2: British (America for the atom bomb... but thats just one weapon. and they massed produced everything else really)
after that: AMERICA!!
I think the correct answer from the choices listed above is option D. The tactic that Charles Townshend use to increase British control of the American colonies would be that created new taxes on the American colonists to raise revenue. Hope this answers the question.
The main political unit that emerged in the world is A. the state. A state is defined as a territory or land in which a defined number of constituents is ruled over a governing body that follows and implements a system without following necessarily a superior power. I think this is powerful enough.
