A student drew a diagram of the quantum model of an atom, as shown. A small circle is shown. Six light gray spheres and six dark gray spheres are shown inside the circle. On the outer side of the circle is another circle of larger radius. This circle has two small circle on its boundary. Another circle of even greater radius is on the outside of the second circle. This outermost circle has four small circles on its boundary.

Which of the following explains if the student's diagram is correct or incorrect?

A - The diagram is incorrect because electrons follow an elliptical path instead of a circular path.

B - The diagram is incorrect because the exact location of the electrons cannot be determined.

C - The diagram is correct because protons and neutrons are concentrated at the center of the atom.

D - The diagram is correct because electrons are present in distinct energy levels around the nucleus.