None of the options provided (alpha decay, gamma decay, beta-minus decay, beta-plus decay) are forms of nuclear fission.
Nuclear fission specifically refers to the splitting of a large atomic nucleus into smaller nuclei, along with the release of energy. The options you've listed are types of radioactive decay:
- Alpha decay: Emission of an alpha particle (2 protons and 2 neutrons).
- Beta-minus decay: Transformation of a neutron into a proton with the emission of an electron.
- Beta-plus decay: Transformation of a proton into a neutron with the emission of a positron.
- Gamma decay: Emission of gamma rays (high-energy photons) from an excited nucleus.
If you are looking for a process directly related to fission, you might want to consider options related to neutron-induced fission or the splitting of heavy nuclei such as uranium or plutonium.