The correct answer is option 3 - Dr. B. R. Ambedkar.
Option 1, Jawahar Lal Nehru, was the first Prime Minister of India, not the first Law Minister. So, option 1 is incorrect.
Option 2, Maulana Abul Kalam Azad, was a prominent leader in the Indian independence movement, but he did not hold the position of the first Law Minister of India. Hence, option 2 is also incorrect.
Option 4, T. Krishnamachari, was a prominent Indian politician and economist, but he did not serve as the first Law Minister of India. Therefore, option 4 is incorrect.
Dr. B. R. Ambedkar, who is the correct answer, was a jurist, social reformer, and politician. He played a crucial role in drafting the Indian Constitution and was appointed as the first Law Minister of India in 1947 by the then Prime Minister, Jawaharlal Nehru. Ambedkar`s contributions in the field of law were significant in shaping the legal framework of independent India.