Why is it necessary to use models to study submicroscopic objects as atoms and molecules

If a hydrogen atom is neutral, it must also have  one electron. an oxygen atom (o) has an atomic number of eight (8). this means a neutral oxygen atom has eight protons and eight electrons. the element actium (ac) has an atomic number of 89, so it has 89 protons and 89 electrons in a neutral atom

The answer is b because c don't explain why the moths are on them and it isn't a because as we know only one species of moth does this