The correct option is "2 and 3 only" because Dr. B.R. Ambedkar founded the All India Scheduled Castes Federation in 1942 to advocate for the rights of Scheduled Castes and promote political representation. He also established the Independent Labour Party in 1936, aimed at addressing the socioeconomic issues faced by the working class. However, the Peasants and Workers Party of India was founded by other leaders and is not associated with Ambedkar, highlighting his distinct focus on caste-based rights and labor issues in his political activism. This understanding underscores Ambedkar's significant role in shaping the political landscape for marginalized communities in India, a key topic in UPSC GS Paper I related to modern Indian history and social reform movements.