The correct answer is: A. Arrah
Swami Sahajananda Saraswati was a social reformer and freedom fighter who set up an ashram at Arrah in Bihar. He was born in 1867 in a village in Arrah district. He was educated at the local school and then at the Patna College. After completing his education, he joined the Indian National Congress and became a close associate of Mahatma Gandhi. He was also a member of the Bihar Legislative Council.
Swami Sahajananda Saraswati was a strong advocate of social reform. He worked for the upliftment of the poor and the downtrodden. He also worked for the education of women and the eradication of untouchability. He was a great leader and a true patriot. He died in 1950.
Option B is incorrect because Patna is the capital of Bihar. Swami Sahajananda Saraswati did not set up an ashram in Patna.
Option C is incorrect because Muzaffarpur is a city in Bihar. Swami Sahajananda Saraswati did not set up an ashram in Muzaffarpur.
Option D is incorrect because Swami Sahajananda Saraswati did set up an ashram at Arrah.