The number of electrons, neutrons and protons in four different particles, A, B, C and D, are shown in the table below.
| Particle | Electrons | Neutrons | Protons |
|---|---|---|---|
| A | 10 | 12 | 12 |
| B | 17 | 18 | 17 |
| C | 18 | 20 | 17 |
| D | 18 | 22 | 18 |
Explain which particle, A, B, C or D, is a negative ion.
