Which of the following is the BEST and MOST objective
restatement of the main idea and important details in
the section "A New Beginning"?

the mongolian invasion of china and central asia resulted in a disruption of the silk road as the chinese garrisons lost support from the chinese kingdoms which fell under the mongols. however, as the mongols established a formal dynasty in china, the successors of genghis khan restored the garrisons along the silk road allowing the safe travel caravans again.

d) all choices are correct

i would go with the last one