Students were shown models of two atoms and asked to make a list of similarities and differences between the models. Which of the statements about the atomic models shown is correct?

A) Both models represent atoms with the same atomic number.
B) Both models represent atoms with the same atomic mass.
C) The model on the left is an ion and the model on the right is an isotope.
D) The model on the left is an isotope and the model on the right is an ion.