Answer : 1. "डॉ राजेंद्र प्रसाद"
Explanation :

Dr. Rajendra Prasad served as the Chairman of the Constituent Assembly of India. He played a pivotal role in guiding the assembly members in drafting the Indian Constitution, which came into effect on January 26, 1950. His leadership and consensus-building skills were crucial in shaping the democratic foundation of the newly independent nation.