He absence of which prominent feature is characteristic of all bacteria?

I dont know answer about this question

Ithink the answer would be f but i couldn’t really see the diagram clearly

The proton has a positive charge while the neutron has no charge they both make up the nucleus of the atom while the elections have a negative charge and surround the nucleus of the atom. the protons and electrons are used to calculate the atom's mass whereas the neutrons don't affect the mass