The correct answer is 1, 2, and 3 because all three individuals were prominent figures who critiqued the economic impacts of colonialism in India. Dadabhai Naoroji, through his work "Poverty and Un-British Rule in India," highlighted the drain of wealth from India due to British exploitation. G. Subramania Iyer was vocal against colonial policies that hampered Indian economic progress, advocating for self-reliance. R.C. Dutt, in works like "The Economic History of India," provided a detailed analysis of how British colonialism adversely affected Indian agriculture and industry. Their critiques collectively underscored the detrimental economic effects of colonial rule, making them key figures in the discourse on colonialism and its economic implications within the framework of Indian nationalism.