C: The stimulation of agriculture by technological innovation
Explanation:
The popularity of Champa rice can be marked to centuries ago when there were not more types of rice cultivated. Champa rice was introduced to the southern part of China from Southern Vietnam. One of the advantages of this crop was that it facilitated double cropping as it matured in less duration. The adoption of machinery and equipment helped to grow the crop in an enormous quantity. Improvement in the irrigation facilities also helped the crops t flourish and grow in a large amount.
The main reason why the US sent troops to overthrow Afghanistan's government in 2001 was because the nation was harboring members of the terrorist group al-Qaeda, which was responsible for the 9/11 attacks.
