The first nuclear explosion undertaken by India was in May:

1974

The correct answer is option (3) - 1974

Another crucial development of the 1970s was the first nuclear explosion undertaken by India in May 1974. Nehru had always put his faith in science and technology for rapidly building a modern India. A significant component of his industrialisation plans was the nuclear programme initiated in the late 1940s under the guidance of Homi J. Bhabha. India wanted to generate atomic energy for peaceful purposes. Nehru was against nuclear weapons. So he pleaded with the superpowers for comprehensive nuclear disarmament. However, the nuclear arsenal kept rising. When Communist China conducted nuclear tests in October 1964, the five nuclear weapon powers, the US, USSR, UK, France and China (Taiwan then represented China)- also the five permanent members of the UN security council- tried to impose the Nuclear Non-proliferation Treaty (NPT) of 1968 on the rest of the world. India always considered the NPT as discriminatory and refused to sign it. When India conducted its first nuclear test, it was termed a peaceful explosion. India argued that it was committed to the policy of using nuclear power only for peaceful purposes.