The most common method of communication in ancient Asia is sending a messenger on a horse. There are transfer stations for horses throughout the continent that allows the messenger to switch to a new horse after covering some distance. Water transportation is also used for communication. In China during an invasion from the North, soldiers on the towers of the Great Wall of China would light up a torch and all the other towers would do that as well until it reaches the capital.
Answer:
Some common things they did was they learned how to hunt and gather food for survival.
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The answer is b)<span> groundwater was overpumped
As population in Mexico City and the </span><span>San Joaquin Valley skyrocketed, the demand for water also increased.
Mexico City was once the most populated city on earth and that created a lot of burden on the cities infrastructure including the water supply.
The groundwater was over pumped leading to huge problems for millions of people.</span>