The correct answer is D) the Sun is between the Earth and a planet. Superior conjunction occurs when a planet is on the opposite side of the Sun from the Earth. This means the Sun is directly between the Earth and the planet, aligning them in a straight line. This configuration is known as superior conjunction. The other options are incorrect because they describe different astronomical phenomena, not superior conjunction. Option A refers to a planet crossing the plane of the Earth's orbit around the Sun. Option B describes the alignment of two planets, not the Sun, Earth, and a planet. Option C describes the maximum northern or southern position of the Sun in the sky, not its alignment with the Earth and another planet.