The correct answer is option 2: 1911. In 1911, Delhi was declared as the capital of India. Before this, the capital of India was Kolkata (formerly known as Calcutta). The decision to shift the capital from Kolkata to Delhi was made during the Delhi Durbar of 1911, which was an imperial gathering held to celebrate the coronation of King George V as the Emperor of India. The reason for the shift was to establish a more centrally located capital that could better represent the entire country. The construction of New Delhi, the city in Delhi that serves as the capital of India, began in 1912 after the announcement. This decision played a significant role in shaping the history and development of the city and the country.