एक प्रजाति द्वारा कब्जा किए गए स्थान के रूप में पारिस्थितिक निकेत (ecological niche) की अवधारणा को मूल रूप से किसने प्रस्तावित किया था?

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?