Answer : 1. "Planetary Motion"
Explanation :

Answer: A) Planetary Motion Explanation: Kepler's laws of planetary motion are three scientific laws describing the motion of planets around the Sun. Kepler’s three laws of planetary motion can be stated as follows: (1) All planets move about the Sun in elliptical orbits, having the Sun as one of the foci. (2) A radius vector joining any planet to the Sun sweeps out equal areas in equal lengths of time. (3) The squares of the sidereal periods (of revolution) of the planets are directly proportional to the cubes of their mean distances from the Sun.