The correct answer is: Dr. Raja Ramanna.
Dr. Raja Ramanna was a nuclear physicist and the founding director of the Bhabha Atomic Research Centre (BARC). He is considered to be the father of India’s nuclear weapons program. He was instrumental in the development of the technology of underground nuclear explosion.
Dr. Homi J. Bhabha was a nuclear physicist and the founding director of the Tata Institute of Fundamental Research (TIFR). He is considered to be the father of Indian nuclear science. However, he did not play a major role in the development of the technology of underground nuclear explosion.
Dr. Vikram Sarabhai was a space scientist and the founder of the Indian Space Research Organisation (ISRO). He is considered to be the father of the Indian space program. However, he did not play a major role in the development of the technology of underground nuclear explosion.
Dr. P. K. Iyengar was a nuclear physicist and the second director of BARC. He was instrumental in the development of the technology of nuclear power generation. However, he did not play a major role in the development of the technology of underground nuclear explosion.