Answer:
?
Explanation: I do not quite understand if you meant to put A. twice and the answers don't really match the question but this is my explanation- Natural barriers, such as mountains, deserts, rivers, and seas, made travel to and from China challenging. The Himalayas in the west and the Gobi in the north were two important geographic barriers. They made the spread of ideas and goods between the ancient Chinese and others outside the region difficult.
