Explanation: Mahatma Gandhi's visit to Champaran in 1917 was a crucial event in the Indian independence movement and marked the beginning of his political career in India. Champaran, located in the state of Bihar, was a region where indigo planters, mostly British, exploited local farmers by forcing them to cultivate indigo and then paying them very low prices for the crop. The farmers were also subjected to harsh penalties if they failed to meet the demands of the planters.
In 1917, Gandhi received a request from a group of farmers in Champaran to help them address their grievances. He traveled to the region to investigate the situation and found that the farmers were indeed being exploited. Gandhi decided to use his method of non-violent civil disobedience to challenge the British authorities and the planters. He organized a series of meetings with the farmers, encouraged them to stand up for their rights, and helped them to present their case to the authorities.
Gandhi's efforts in Champaran were successful in bringing attention to the plight of the farmers and eventually led to the passing of the Champaran Agrarian Act in 1918, which aimed to improve the conditions of the farmers. This event is significant because it was the first time Gandhi used his philosophy of non-violent resistance in India, and it set the stage for his future leadership in the Indian independence movement.
The year 1917 is therefore the correct answer, as it marks the beginning of Gandhi's political activism in India and the use of non-violent civil disobedience as a tool for social and political change. The other years mentioned in the options are significant in their own right but are not related to Gandhi's visit to Champaran. For example, 1920 is the year of the Non-Cooperation Movement, 1906 is the year of the Surat Split in the Indian National Congress, and 1915 is the year Gandhi returned to India from South Africa.