Who founded the Arya Samaj?

Concept: In colonial 19th-century India, several socio-religious reform movements arose to address perceived weaknesses in Hindu society and religion. These movements differed sharply in orientation: some (like Arya Samaj) sought to purify Hindu practice by returning to the authority of the Vedas and rejecting later accretions such as idol worship, birth-based caste discrimination, and child marriage; others (like Brahmo Samaj) built a monotheistic reform faith influenced by Christian and Islamic ideas and did not accept Vedic ritual authority as final; and still others were revivalist philosophical schools that predate the colonial reform era entirely.

Application: Swami Dayanand Saraswati founded the Arya Samaj on 7 April 1875 in Bombay. He grounded the organisation's teaching in the doctrine 'Back to the Vedas', campaigning against idol worship, caste discrimination by birth, untouchability, and child marriage, while promoting the Shuddhi movement of religious reconversion. His major text, Satyarth Prakash, lays out these Vedic-revivalist principles.

Cross-check: Checking each named figure against the historical record confirms the option-set is exclusive: Adi Shankaracharya lived in the 8th century CE, centuries before colonial India, and is known for systematising Advaita Vedanta philosophy and establishing the four mathas — he is unconnected to the 19th-century reform movements. Swami Vivekananda founded the Ramakrishna Mission in 1897, a distinct organisation built around Vedanta philosophy and the teachings of Ramakrishna Paramahamsa, not the Vedic-revivalist Arya Samaj. Raja Rammohan Roy founded the Brahmo Samaj in 1828, a reform body that moved away from Vedic ritual authority rather than reviving it, making its orientation the opposite of Arya Samaj's.

Result: The founder of the Arya Samaj is therefore Swami Dayanand (Saraswati).