he most important new crop introduced during the Tang and Song periods wasGroup of answer choicescottonfast-ripening riceindigoorangesbarley

The most important new crop introduced during the Tang and Song periods was fast-ripening rice.

This variety of rice significantly increased agricultural productivity, allowing farmers to cultivate rice in regions that were previously unsuitable for its growth. The introduction of fast-ripening rice enabled multiple harvests in a single growing season, which contributed to population growth and urbanization during this time. Additionally, it supported the economic expansion of the Tang and Song dynasties, leading to increased trade and the development of a more complex society. While cotton, oranges, and other crops were also important, fast-ripening rice had the most profound impact on agriculture and society during these periods.