I think it does not stand for anything specific
The Boston massacre came before the tea party. (Massacre 1770, and Tea party 1773)
President Truman had the urge to use the atomic bomb against Japan because the American casualties would continuously rise unless the Empire of Japan surrenders. The thing that would make Japan surrender would be a cataclysmic event, and the bombing of Hiroshima and Nagasaki happened.
Answer:
I believe it is C
I asked my history teacher about this and she said it is right. Also I believe trade these days does not relate that much to political history.
So sorry if I am wrong