What scientific advancement is described as a nuclear weapon that releases energy through nuclear fission?

The atomic bomb is accurately described as a nuclear weapon that releases energy through nuclear fission, which is the process of splitting heavy atomic nuclei, such as uranium-235 or plutonium-239. When these nuclei are split, they release a substantial amount of energy in the form of an explosion. This phenomenon was first harnessed during World War II, leading to the development of bombs that were dropped on Hiroshima and Nagasaki.

In having a clear understanding of fission, it is significant to distinguish the atomic bomb from the other mentioned devices. The hydrogen bomb, for instance, utilizes nuclear fusion—combining light atomic nuclei to form heavier ones—and is vastly more powerful than an atomic bomb. A nuclear reactor, while it also uses fission to generate energy, is designed for controlled reactions to produce electricity rather than as a weapon. The neutron bomb, a type of thermonuclear weapon, is engineered to release a high proportion of energy in the form of neutrons, which can cause significant damage to living organisms while minimizing physical destruction to buildings and infrastructure. Hence, the atomic bomb specifically refers to the weapon that derives its explosive energy from nuclear fission, making it the correct choice in this context.