The Mahad Satyagraha of 1927 was organized by B. R. Ambedkar.

Option 1: B. R. Ambedkar - This is the correct answer. B. R. Ambedkar, a social reformer and leader of the Dalit community, organized the Mahad Satyagraha. The objective of the satyagraha was to fight for the right of Dalits to access water from public water sources in Mahad, Maharashtra.

Option 2: Mahatma Gandhi - Mahatma Gandhi, known for his leadership in the Indian independence movement, was not directly involved in the Mahad Satyagraha.

Option 3: S. C. Bose - Subhas Chandra Bose, a prominent figure in the Indian independence movement, was not involved in organizing the Mahad Satyagraha.

Option 4: Lokmanya Tilak - Lokmanya Tilak, a freedom fighter and nationalist leader, was not involved in the organization of the Mahad Satyagraha.

In conclusion, the Mahad Satyagraha of 1927 was organized by B. R. Ambedkar.