Step-by-step explanation:
As the distance between a planet and the sun increase, the following quantities will decrease.
1. The gravitational force is given by :

As the distance between a planet and the sun increase, the gravitational force decrease.
2. As the distance between a planet and the sun increase, it result in the decrease in its speed. Due to decrease in gravitational force, centripetal force acting on the planet should decrease. Since,

v is the tangential speed
So, the tangential speed must decrease.
3. The distance traveled in a day should decrease.
Hence, this is the required solution.