निम्नलिखित में से कौन सा नत्रजनीय जैव उर्वरक के रूप में प्रयुक्त होता है?

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?