Respuesta :

A. Oxygen. Oxygen has an atomic mass of 16. The atomic mass of an atom is the combined weight o the protons and neutrons. Since Oxygen's atomic mass is 16, it has 8 protons and 8 neutrons.
Oxygen, you cannot judge an elements number of protons by its atomic mass, but by the atomic number. the atomic number is 8, thus 8 protons.