China is trying to halt the spread of the gobi desert by a. build canals through it, b, plant more trees c. improve water quality d. damming rivers

B, plant more trees

Explanation:

The Gobi desert located in china cover about 1600 km from the southwest and has an area of  1,295,000 km square, forming an arc-shaped island and is the six largest desert in the world. Its a sandy desert and is mostly exposed to bare rocks. As its a cold desert type of climate, mostly the dominance in the far north. The Gobi desert is growing at an alarming rate on the southern edge of china and china is tackling this problem through the green belt or wall of trees.

Europeans are more concentrated in urban areas.

C.about 10% i think