Answer:
Option (3)
Explanation:
Given that, planet Y is at a distance of 1 AU away from the sun, and the planet Z is at a distance 0.39 AU away from the sun.
From Kepler's law of astronomical unit, it is known that the planets that are closer to the sun move at a faster rate in comparison to the distant planets because of their high gravitational force.
So from the given condition, it can be concluded that the planet Y is at a greater distance (1 AU) from the sun, which will orbit the sun at a much slower rate because of its comparatively weaker gravitational force, as the speed of a planet is directly affected by the distance from the sun.
Thus, the correct answer is option (3).