The correct answer is option 2, H. H. Risley. In 1904, H. H. Risley, a colonial administrator, made the declaration about the partition of Bengal. He believed that a united Bengal was a powerful force, but if Bengal was divided, it would result in different factions pulling in different directions, causing instability.

Option 1, Lord Curzon, was the Viceroy of India during the time of the Bengal partition, but there is no evidence to suggest that he made this specific declaration.

Option 3, Lord Minto, was the Viceroy of India before the partition of Bengal. There is no evidence to suggest that he made this specific declaration either.

Option 4, Sir Lancelot Hare, was an administrator in India during the time of the partition of Bengal, but there is no evidence to suggest that he made this specific declaration.

It is important to note that the provided answer is generally correct. However, if additional evidence is found that contradicts this answer, it might be necessary to reconsider the accuracy of the provided answer.