Salutary Neglect was the policy that had caused the British to not enforce various laws in the American colonies. The British dis not really mean to do this. There were other more pressing matters that occupied their time. The colonies were more of less following the laws. Britain would not become completely aware of how much the colonies were working outside the laws until the French and Indian War. The war opened the eyes of the British to how the colonists were actually conducting business.
The answer that best applies to both the Tang and Song dynasties would be C. A Reliable food production and distribution system. This gave both dynasties the ability to thrive.