The partition of Bengal in 1905 was realized during the Viceroy-ship of:

Lord Curzon

The correct answer is Option (4) → Lord Curzon

The Partition of Bengal (1905) was announced on 19 July 1905 and implemented on 16 October 1905 during the viceroyalty of Lord Curzon (Viceroy of India from 1899 to 1905). It divided Bengal into two provinces (largely along religious lines) for administrative reasons, sparking widespread protests and the Swadeshi Movement, and was annulled in 1911.