Keshab Chandra Sen was a prominent social reformer and leader of the Brahmo Samaj movement in Bengal. He played a significant role in founding the Tabernacle of New Dispensation in 1864, which sought to promote a more modern, universal interpretation of religion, distinct from orthodox practices. Additionally, he was instrumental in the establishment of the Indian Reform Association in 1870, which aimed at social reform and improving the conditions of the Indian populace. However, the Calcutta Unitarian Committee was not directly associated with him, making the correct answer 2 and 3 only. This highlights the interconnections between religious reform and social movements in colonial India, reflecting significant changes in Indian society during that period.