Q. The longest border between any two countries in the world is between:
Answer: A
Notes:
Exp) Option a is the correct answer.
Option a is correct. Canada and the United States shares the longest international land border measuring 8,893 Km. The border is divided into two: the border shared with Canada by the continental United States and the border that the state of Alaska shares with northern Canada.
Source: https://www.worldatlas.com/articles/countries-with-the-longest-land-borders.html

