The correct option is B β- emission
In a β - emission, a neutron dissociates itself into a proton and an electron. While emitting a β - particle, the total number of nucleons in nucleus an atom remains the same, but the number of neutrons is decreased by one and the number of protons is increased by one. The reaction is as follows
AZX →AZ+1Y + 0−1e(β) + Energy