Which of these characteristics applies to both the tang and song dynasties?
a. policies promoting progress toward social equality for women
b. a reliable food production and distribution system
c. religious leadership based on chan buddhism
d. population shifts from urban to rural areas of china

The best option regarding characteristics that apply to both the Tang and Song dynasties would be "b. A reliable food production and distribution system," since this was a major way in which both of these societies were allowed to thrive. 

b. A reliable food production and distribution system

The Tang and Song Empires were successful at creating increased food production. Irrigation systems were responsible for more growing areas and particularly helped produced more rice. The empires also manipulated the landscape to create more land to farm. Terrace systems within the land also increased the amount of land that could be farmed at any one time. Cotton, tea, and rice became the most produced crops making money for the empires.