Canada's border with the United States is the world's longest international border, at 8,890 km. This compares with the 6,846-km boundary between Russia and Kazakhstan and the 5,308-km frontier between Chile and Argentina. India shares 3488 Km of border with China that runs along the Union Territory of Ladakh, States of Himachal Pradesh, Uttarakhand, Sikkim and Arunachal Pradesh. Hence option (a) is the correct answer.