To be honest, I dont know. I'm actually not an American. :)
But If i had to pick one major event...it would be making George Washington the president.
To explane.
George Washington's presidentsy in a way made America, in some aspects, what it is today.
Now imagine if he was not made a president but chose to be a dictator. I know its funny and my nest statement is going to be even funnier.
Assassins Creed 3: The rule of King George did a decadent job in imagining and explaning this. I recommend reading its plot, I think you would find it interesting. Its full of what ifs and alternative history events.
Sorry for not giving my version but its a bit hard for me to imagine something like that.
The overinflated stock market helped cause the Great Depression when the stock market burst and all of the prices started to fall drastically.
Patrick Henry, a great orator from Virginia was the one who raised his voice against the British policies. He was a lawyer and patriot and gave the famous slogan " give me liberty or give me death ". He was the one who supported right to bear arms and fought against the stamp act. He was one of the founding fathers of American revolution and after Declaration of Independence he was made the governor of Virginia.
Your answer will be c, hope this helps :)