The correct answers are A) telescopes and persistent inquiry and C) determining the laws of planetary motion.
What contributed to Kepler's discovery that the Earth's orbit was actually an ellipse were telescopes and persistent inquiry and C) determining the laws of planetary motion.
Kepler defined the orbits through three laws. The first one, the law of orbits, that says that all planets move in elliptical orbits around a central point, the Sun. The second one, that says that a line that connects a planet to the Sun, sweeps out equal areas in equal times. And the third one thay says that the square of the period of any planet is proportional to the cube of the semi major axis of its orbit. With these laws changed the way astronomers study the solar system.
