An atom is considered neutral when the number of protons (which are positively charged) is equal to the number of electrons (which are negatively charged).
- The first option has 8 electrons and 8 protons; it is neutral.
- The second option has 9 electrons and 8 protons; it is negatively charged (anion).
- The third option has 4 electrons and 6 protons; it is positively charged (cation).
- The fourth option has 16 electrons and 18 protons; it is negatively charged (anion).
Therefore, the only neutral atom in the given options is the first option: an oxygen atom with 8 electrons, 8 protons, and 9 neutrons.