The correct answer is option 'A', Jotiba Phule.

Jotiba Phule was a social reformer, thinker, and activist who played a significant role in the social and educational upliftment of the marginalized communities in India. He founded the Dinbandhu Sarvajanik Sabha in 1884 as a platform to advocate for the rights and welfare of the lower castes and untouchables.

**The Dinbandhu Sarvajanik Sabha:**
The Dinbandhu Sarvajanik Sabha, also known as the Native Public Association, was established by Jotiba Phule in Pune, Maharashtra in 1884. It was one of the earliest organizations in India dedicated to social reform and the upliftment of the oppressed communities.

**Objectives:**
The main objective of the Dinbandhu Sarvajanik Sabha was to address the social inequities prevailing in society, particularly the caste-based discrimination and oppression faced by the lower castes and untouchables. The Sabha aimed to create awareness among the masses, promote social equality, and fight for the rights of the marginalized sections.

**Activities:**
The Sabha organized various activities and initiatives to achieve its objectives. It conducted public meetings, seminars, and discussions to raise awareness about caste-based discrimination and the need for social reform. The Sabha also played a crucial role in spreading education among the lower castes and untouchables by establishing schools and educational institutions.

**Impact:**
The establishment of the Dinbandhu Sarvajanik Sabha was a significant step towards creating a platform for the oppressed communities to voice their concerns and fight for their rights. It laid the foundation for the social reform movements that followed and inspired many other individuals and organizations to work towards social equality.

**Jotiba Phule's Contribution:**
Jotiba Phule, along with his wife Savitribai Phule, was at the forefront of the social reform movement in Maharashtra. He challenged the orthodox Brahmanical social order and fought against caste-based discrimination. Through his writings, speeches, and activism, he advocated for the rights and empowerment of the lower castes and untouchables. The establishment of the Dinbandhu Sarvajanik Sabha was one of his initiatives to bring about social change.

Phule's work laid the foundation for the future social reform movements led by leaders like B.R. Ambedkar and D.K. Karve. His ideas and efforts continue to inspire and guide the fight against social inequality and injustice in Indian society.

In conclusion, Jotiba Phule founded the Dinbandhu Sarvajanik Sabha in 1884 as a platform to advocate for the rights and welfare of the lower castes and untouchables. The Sabha played a significant role in raising awareness about social inequality and promoting social reform in India.