An isotope-production computer records a nucleus with mass number 188 and atomic number 76. After exactly two emissions, the recorded nucleus has mass number 184 and atomic number 74. The possible emissions are alpha particles, beta-minus particles, beta-plus particles, gamma photons and neutrons.
Which pair of emissions produced the recorded nucleus?
one alpha particle and one gamma photon
two beta-plus particles
one alpha particle and one beta-minus particle
two neutron emissions