Answer : 4. "1905"
Explanation :

The Partition of Bengal occurred in 1905 when the British colonial administration decided to divide the province of Bengal in British India. The primary stated reason was administrative efficiency, but it had significant political implications. The partition led to widespread protests and opposition from various communities, particularly due to concerns about communal tensions and political motivations. In response to the widespread protests, the British government annulled the partition in 1911 and reorganized Bengal. The event had lasting effects on the political consciousness of the region and contributed to the development of political movements in India.