Correct Answer:
A. Swami Dayananda Saraswati
The Arya Samaj, a significant Hindu reform movement, was founded by Swami Dayananda Saraswati in 1875. His primary objective was to revive Vedic values and practices, advocating for a return to the original teachings of the Vedas and rejecting idol worship and caste distinctions. Swami Vivekananda, on the other hand, founded the Ramakrishna Mission, focusing on spiritual and humanitarian service. Keshav Chandra Sen was a prominent leader of the Brahmo Samaj, another reformist movement. Ishwar Chandra Vidya Sagar was a social reformer known for his work on widow remarriage and education, but not associated with the founding of Arya Samaj.