Correct Answer:
B. Second Anglo-Afghan War
The Durand Line, which demarcates the border between Afghanistan and Pakistan, was formed after the Second Anglo-Afghan War (1878-1880). It was established in 1893 by Sir Mortimer Durand and Abdur Rahman Khan, the Amir of Afghanistan, as a result of British imperial policy in the region.
- The First Anglo-Afghan War (1839-1842) and Third Anglo-Afghan War (1919) occurred at different times and were not directly responsible for the line's formation.
- WWI (1914-1918) was a global conflict and not directly related to the establishment of this specific border.