निम्नलिखित में से किस अनुसंधान पद्धति में अन्वेषक जानबूझकर एक चर में हेरफेर करता है ताकि दूसरे में परिवर्तनों का अवलोकन किया जा सके, जिससे कार्य-कारण संबंध स्थापित होते हैं?

Which Indian independence movement leader was primarily known for his philosophy and practice of non-violent civil disobedience?

Who gave the call for 'Do or Die' during the Quit India Movement in 1942?

Which of the following revolutionary pairs were imprisoned together in Cellular Jail and faced harsh conditions, contributing significantly to the Indian independence movement?