ज्वालामुखी फटने और ढहने पर बनने वाले बड़े कड़ाही जैसे खोखले गड्ढे को क्या कहा जाता 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?