In which year did the First Anglo-Afghan War begin?
The First Anglo-Afghan War began in 1839 CE. It was fought when the British East India Company intervened in Afghanistan and supported Shah Shuja in an attempt to strengthen its political position on the north-western frontier. The conflict continued for several years and became a difficult episode in British imperial and frontier policy. For this question, the required fact is the starting year, not the later stages or the final consequences.
Option B, 1839 CE, is correct. The other years do not match the beginning of this war: 1833, 1845 and 1849 refer to different events or periods in nineteenth-century history. A useful memory link is “First Anglo-Afghan War—1839,” while taking care not to confuse its beginning with later military developments. Therefore the supplied answer is historically consistent.