The social reformer who established the Satyashodhak Samaj was:

Jyotirao Phule
B.R. Ambedkar
Gopal Ganesh Agarkar
Vinoba Bhave

The correct answer is Jyotirao Phule.

Jyotirao Phule was a social reformer and thinker who is considered to be one of the founding fathers of modern India. He was born in 1827 in Pune, Maharashtra, India. He was a pioneer in the field of women’s rights and education, and he also worked to improve the lives of the lower castes in India. He founded the Satyashodhak Samaj in 1873, which was a social reform movement that aimed to improve the lives of the lower castes and women in India.

B.R. Ambedkar was a social reformer, politician, and jurist who is considered to be the father of the Indian Constitution. He was born in 1891 in Mhow, Madhya Pradesh, India. He was a Dalit, or member of the lowest caste in India. He worked to improve the lives of the Dalits and other lower castes in India, and he also fought for the rights of women. He founded the Bahujan Samaj Party in 1984, which is a political party that represents the interests of the Dalits and other lower castes in India.

Gopal Ganesh Agarkar was a social reformer, journalist, and politician who was born in 1856 in Pune, Maharashtra, India. He was a pioneer in the field of journalism, and he also worked to improve the lives of the lower castes in India. He founded the Kesari newspaper in 1881, which was a Marathi-language newspaper that was critical of the British Raj.

Vinoba Bhave was a social reformer, Gandhian activist, and spiritual leader who was born in 1895 in Gagode, Maharashtra, India. He was a follower of Mahatma Gandhi, and he worked to promote Gandhian principles of non-violence and social justice. He founded the Bhoodan movement in 1951, which was a movement that aimed to redistribute land to the landless.