Answer:
It proclaimed the freedom of slaves in the ten Confederate states still in rebellion. It also decreed that freed slaves could be enlisted in the Union Army, thereby increasing the Union's available manpower.
So I'm guessing D or B.
I'm pretty sure that they opened the first Silk Road
During this era, human technology boomed. In this era, nomads have started farming. Nomads have stopped moving from one place to another. They have started forging metal tools. They also started pastoralism. They have communities and tribe. They were able to create a system on their own.
It bankrupted the Soviet Union. The US private sector was able to develop the new technology and created new products and industries.