The table shows a sequence of nuclear changes.
| Nucleus | Mass number | Atomic number |
|---|---|---|
| P\mathrm{P}P | 216 | 84 |
| Q\mathrm{Q}Q | 212 | 82 |
| R\mathrm{R}R | 212 | 83 |
| S\mathrm{S}S | 211 | 83 |
Which sequence of emissions produces these changes?
neutron, then beta-minus, then alpha
neutron, then beta-plus, then alpha
alpha, then beta-plus, then neutron
alpha, then beta-minus, then neutron