The correct answer is option 3, Dr. B.R. Ambedkar. Dr. Ambedkar was a prominent Indian social reformer and politician who dedicated his life to advocating for the rights of oppressed and backward classes in India. He played a crucial role in the drafting of the Indian Constitution and fought for social equality and justice. Ambedkar`s efforts were centered around uplifting the Dalits, also known as the "untouchables," and he worked towards abolishing discrimination, untouchability, and caste-based oppression. He also emphasized the importance of providing education and economic opportunities to marginalized communities. Through his activism, writings, and political work, Dr. Ambedkar fought for the empowerment and dignity of oppressed classes, making him a key reformer in addressing social injustices in India.