What is different about the atomic structure of the oxygen isotopes?

Each isotope of oxygen contains 8 protons, but differs in the number of neutrons. An isotope number is a shorthand representation of its mass. Because protons and neutrons are roughly equal in mass, an isotope's number is equal to the sum of its protons and neutrons.

Explanation:

Isotopes are atoms of the same element that have different numbers of neutrons but the same number of protons and electrons. The difference in the number of neutrons between the various isotopes of an element means that the various isotopes have different masses.

the answer is either b or c

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.