What was the Silk Road? a series of roads that were covered in silk imported from China
a four-thousand-mile canal used from 1300 BCE to 1453 CE
a single ancient trade road that connected China and Japan
a series of ancient trade routes that connected China with Europe and East Africa

D.a series of ancient trade routes that connected China with Europe and East Africa

Explanation:

The answer is D because it was a trade route connecting China, Europe, East Africa during the 130 b.c it was used for trading such as gold, silver, and many more. There's was a problem with the silk road because the first geography route was complicated and most of the passages they traveled on were narrow and somewhat dangerous, There's was also diseases spreading such as chicken pox, Measles.

B, Sharply Increased.

Explanation:

I say this, because 12 million people came to the US in that time period, and many probably went to Washington.