Answer:
Air pollution from smokestacks will be the biggest challenge.
Step-by-step explanation:
China is one of the biggest producers in the world of agricultural goods. The country has a long tradition of being among the leaders in the world in this sector, even when it has been in terrible conditions. One thing that is a problem though is that the area where agricultural activities take place in China is not that big. This is due to the country's geography.
But it seems that geography won't be the biggest problem, but the pollution of the air. China has become heavily industrialized and in order to reach the level at which it is now, it did not take the environment into account at all. The pollution has constantly been increasing and it affects agriculture as well. Because the air pollution is at a very high level, there are more and more acid rains, but also they partially block the sunlight. The acid rains destroy the plants, which is already causing problems and they will only just increase. By blocking the sunlight in some areas, the plants grow slower and produce less because they cannot perform photosynthesis properly.