Which statement is true regarding Champaran Satyagraha?

• A. In 1917 AD, the first experiment of Satyagraha was done by Mahatma Gandhi in Champaran.
• B. Gandhiji agreed to come to Champaran only on the request of Rajkumar Shukla.
• C. Gandhi reached Patna on 10 April 1917 via Calcutta.
• D. all of the above are true