निम्नलिखित में से किस प्रक्रिया में ऊष्मा का संचरण बिना किसी भौतिक माध्यम के 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?