Final answer:
The duration of British Imperialism in India was from 1858 to 1947, also known as the British Raj period, which started after the suppression of the Sepoy Mutiny and ended with India's independence.
Step-by-step explanation:
The duration of British Imperialism in India lasted from 1858, when the British government took direct control following the suppression of the 1857 Sepoy Mutiny, until 1947, when India gained independence. This period is known as the British Raj, and it signifies a time of direct British rule, marked by the crowning of Queen Victoria as Empress of India in 1876, and the governance of India by British officials. The correct answer to the student's question is Option 1: 1857 - 1948 CE, reflecting the time from the rebellion to just after India achieved independence, although the official transfer from the East India Company to the British Crown occurred in 1858, and independence was formally achieved on August 15, 1947.