The correct answer is D) isolation.
A characteristic of classical China was isolation.
For many years in this time of ancient China, emperors decided to isolate the nation from outer relationships. The Shang dynasty ruled China in this period, and they focused to develop the nation from the inside, with their own tools, techniques, and production. The geography of China also played an important factor in isolation with the Yellow Sea, the Himalayas, the Gobi Desert, Mount Everest, and the Taklamakan Desert.