Identify the group of classes that best represents a Venn diagram relationship where one set is entirely contained within a second set, which in turn is entirely contained within a third set (concentric circles).

The 'Drain of Wealth' theory was propounded by which Indian nationalist leader?

Which event is considered the turning point in Mahatma Gandhi's leadership in the Indian independence movement?

Which African leader is known for his non-violent opposition to colonial rule?