What most contributed to the diffusion of ideas from Tang and Song China to Europe? the reinstatement of civil service exams for government officials
the creation of social services and a strong economy
the overthrow of the emperor by the Mongols
the trade along the Silk Road

the trade along the Silk Road

Explanation:

The trade along the Silk Road has been known to have a great contribution to the diffusion of ideas from Tang and Song China to Europe. This routes coupled with maritime trade the Persian Gulf and Red Sea, saw exchange of commodities between the Chinese and other parts of the world, particularly the Middle East, India, and Europe. These trading activists also involved cultural exchanges such as songs, dances, and musical instruments

the doctrine of nullification recommended that states living inside the union have the one-sided, inalienable ideal to void any law made by the national government that could be esteemed illegal.

the united states was shaped based on a general agreement among its individual states. hence, it is inferred that under the hypothesis of invalidation, since the states are the establishment of the union, they have the ability to referee and disprove unlawful laws.