किस ऐतिहासिक सर्वोच्च न्यायालय के निर्णय में 'मूल संरचना सिद्धांत' (Basic Structure Doctrine) स्थापित किया गया था, जिसने संविधान की आवश्यक विशेषताओं को संशोधित करने की संसद की शक्ति को सीमित किया?

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?