China has the longest border with which of the following country

China shares land borders with 14 sovereign states, making it one of the countries with the most neighbors. Among the given options, Mongolia has the longest land border with China, stretching approximately 4,677 kilometers (2,906 miles). This extensive border runs across diverse terrains, including deserts and grasslands, and is a significant geographical feature.

• Russia shares a long border with China, but it is shorter than the border with Mongolia, approximately 4,209 km.

• Myanmar shares a border with China, but it is significantly shorter than those with Mongolia or Russia.

• None of these is incorrect, as Mongolia holds the distinction of having the longest border with China among the choices.