In the context of the Indian freedom struggle, 16th October 1905 is well known for which one of the following reasons?

The correct option is B because 16th October 1905 was the day the Partition of Bengal, announced by Lord Curzon, officially came into force. This day was observed as a day of national mourning throughout Bengal. People fasted, walked barefoot to the Ganges for a bath, and sang patriotic songs. It also marked the beginning of the Raksha Bandhan celebration, suggested by Rabindranath Tagore, where people tied threads on each other's wrists as a symbol of unity between Hindus and Muslims against the British policy of divide and rule. Regarding the other options: The formal proclamation of the Swadeshi Movement was made on 7th August 1905 at the Calcutta Town Hall. Dadabhai Naoroji declared Swaraj as the goal of the Congress during the Calcutta Session in 1906. While Tilak was a major leader of the movement, the date 16th October is specifically tied to the implementation of the partition itself.