Dadabhai Naroji`s theory of "Drain of Wealth" is described in his book "Poverty and Un-British Rule in India". This theory explains how British colonization in India led to the economic exploitation and depletion of India`s resources. Naroji argued that the British Raj was draining India of its wealth by extracting resources and sending them back to Britain, resulting in poverty and underdevelopment in India. His book discussed various aspects of this drain, including the unequal economic policies, the exploitative nature of British rule, and the negative impact it had on India`s economy. Naroji`s theory played a significant role in shaping the nationalist movement in India and highlighting the economic injustices inflicted by British colonization. Therefore, option 1 is the correct answer.