I believe the answer is: B.because of advances in science, medicine, technology, and the arts
During the hand civilization, China developed many advancement in use of herbs for medicinal purpose and adopted many technology from all across the world which increase their agricultural production capacity.
Their artworks were also developed to the point where it became a hot commodity among European nobles.
the medieval knightly system with its religious, moral, and social code.
courteous behavior, especially that of a man toward women.
Decreasing nationalism is the answer.