Correct Answer:
D. New Mexico
The world's first nuclear explosion, codenamed the Trinity test, occurred on July 16, 1945. This pivotal event was the culmination of the top-secret Manhattan Project, designed to develop the atomic bomb.
The correct answer is New Mexico. The test took place at the White Sands Proving Ground in New Mexico, USA, marking a new era in human history.
Hiroshima and Nagasaki are incorrect because these were the Japanese cities where atomic bombs were dropped in August 1945, *after* the Trinity test, as acts of war, not the site of the initial experimental explosion. Rajasthan is also incorrect; it is a state in India, which conducted its first nuclear test much later in 1974, unrelated to the world's first nuclear detonation.