A watershed is a certain area that separates water from flowing into rivers/seas.
Answer:
Answer: Plains occur as lowlands along the bottoms of valleys or on the doorsteps of mountains, as coastal plains, and as plateaus or uplands. ... Plains may have been formed from flowing lava, deposited by water, ice, wind, or formed by erosion by these agents from hills and mountains.
B; As far as the relation between humans and the environment, it is obvious how much they relied on it. Not only as a food source, but for economic growth and sustainability as well. The other answers make valid points but in the context of this question, the only one that even mentions the relation is B.
The desert regions in China that are largely uninhabited are the Iner Mongolia region on the north of the country, and the Xinjiang region on the west of the country.
Saudi Arabia is a country that in most part is uninhibited and people are concentrated in the cities which are surrounded by desert and some partially from sea. The most uninhabited regions are Northern Borders, Jawf, Bahah and Najran.