The correct answer is A. 1839.
The First Anglo-Afghan War was a conflict between the British Empire and the Emirate of Afghanistan from 1839 to 1842. The war was caused by a British desire to control Afghanistan and to prevent it from falling under Russian influence. The British invaded Afghanistan in 1839 and quickly captured the capital city of Kabul. However, the British were unable to control the country and were eventually forced to withdraw in 1842. The war was a disaster for the British, who suffered heavy casualties and lost all of their influence in Afghanistan.
Option B is incorrect because the Second Anglo-Afghan War took place in 1878-1880.
Option C is incorrect because the Third Anglo-Afghan War took place in 1919.
Option D is incorrect because the First Anglo-Afghan War did not take place in 1833.