Answer:A proton
Step-by-step explanation:
In nuclear physics, beta decay is a type of radioactive decay in which a beta ray is emitted from an atomic nucleus. For example, beta decay of a neutron transforms it into a proton by the emission of an electron accompanied by an antineutrino, or conversely a proton is converted into a neutron by the emission of a positron .... Thus, according to Fermi, neutrinos are created in the beta ...