Final answer:
In 1920, Gandhi was defined by his leadership in the Indian National Congress, where he advocated for nonviolence and civil disobedience in the Indian independence movement.
Step-by-step explanation:
The important factor that defined Mohandas (Mahatma) Gandhi in 1920 was a) His leadership in the Indian National Congress. During this time, Gandhi became the head of the Indian National Congress in 1921, and it was rapidly transforming into the voice of the masses.
Gandhi's approach involved advocating for civil disobedience and nonviolence, which were key strategies in the movement for self-rule and independence in India. His embrace of asceticism and simplicity, along with his nonviolent methods, were central to his identity and his leadership within the Congress Party.