Final answer:
The two parts of an atom are the nucleus, which contains protons and neutrons, and the electron cloud, which has orbiting electrons. Correct option is d)
Step-by-step explanation:
The two parts of an atom consist of the nucleus and the electron cloud. The nucleus is at the center of the atom and contains subatomic particles known as protons, which have a positive electric charge, and neutrons, which have no electric charge. Surrounding the nucleus is the electron cloud, which is a diffuse cloud of negative particles called electrons that orbit the nucleus. The correct answer to the question, "What are the two parts of an atom?" is d) the nucleus and the electron cloud.