The correct answer is option 3, Mahatma Gandhi. Mind Swaraj is a book written by Mahatma Gandhi. In this book, Gandhi presents his thoughts on various topics such as politics, spirituality, economics, and education. The book serves as a guide to achieving self-rule or "Swaraj" through inner transformation.

Option 1, Aurobindo Ghose, is not the correct answer because he is not the author of Mind Swaraj. He was a philosopher, yogi, and political leader in India, but he did not write this book.

Option 2, C.R. Das, is also not the correct answer. Although Das was a prominent figure in the Indian independence movement, he was not the author of Mind Swaraj.

Option 4, Rajendra Prasad, is incorrect as well. Rajendra Prasad was the first President of India, but he did not write Mind Swaraj.

In conclusion, Mahatma Gandhi was the author of Mind Swaraj, which is a book that delves into his ideologies and ideas for achieving self-rule.