Golly this one sure is hard. It eliminated the need for mail to be carried via roads or rail lines, and things (and people) could be carried directly to the destination's nearest airport instead of all the way down the winding roads to it.
Scary for everyone cause he started a war
scratch that: the SECOND WORLD WAR!!!
The correct answer is - D. how to make iron.
The Zhou dynasty was one of the greatest dynasties of China, and among many achievements of their reign, the artisans of this dynasty managed to learn how to make iron. This was revolutionary for the Chinese people, and it was of great use in the agriculture after the tools for it started to come in iron version, and it made everything much easier, quicker, and more efficient.
John quincy adams (son of john adams the second president of the united states) was the 6th president of the us
