Correct Answer: Mongolia

Solution : The correct answer is Mongolia .

China shares its borders with 14 nations, namely Afghanistan, Bhutan, India, Kazakhstan, North Korea, Kyrgyzstan, Laos, Mongolia, Myanmar, Nepal, Pakistan, Russia, Tajikistan, and Vietnam. The longest border of China is shared with Mongolia, followed by Russia, and India. India, on the other hand, has the longest land border with Bangladesh. Moreover, the world's longest international border exists between Canada and the United States of America.