In the diagram, planets a, b, and c have the same mass. which of these statements is true about the motion of these planets? planet a will take the longest time to complete an orbit, while planet c will take the shortest time. planet a will take the shortest time to complete an orbit, while planet c will take the longest time. the combined gravity of planets a and c will cause planet b to take the longest time to orbit. all the planets will take the same amount of time to complete one orbit.

A,B,C are three planets with the same mass,then it means they have also the same gravity,so what matters here is the distance between the Sun,more exactly,their orbits.
⇒ The shorter the distance from the Sun, the more a planet completes an orbit. ⇒ Correct affirmation : Planet A will take the shortest time to complete an orbit, while planet C will take the longest time.

The first affirmation is false because the planet A is the closest to Sun,so logically,it will complete the orbit faster than the others.

The affirmations 3 and 4 are incorrect because their gravity is equal and because the distance between the planets and the Sun differs from one planet to another.

By his speech’s did he live up too his expectations