There were a lot of factors in different countries but the most notable one is the conflict of interest. The king and his nobles didng get along anymore as the nobles found the ruling pointless.
No extinction of humans not sure
The answer would be the first one. America was working at close hands with Japan at the time of the development of the open door policy. Because of this act, China is the leading manufacturer in most things made in America and Japan. hope this helps!
