Gravity Holds Solar System Practice Test

Two models are shown for the same Sun–planet system. In Model 1, gravity arrows point from the planet toward the Sun (larger mass), and the planet has a forward velocity arrow along a curved orbit path. In Model 2, the planet has the same forward velocity arrow but no gravity arrows are shown.

Which model best explains a stable orbit (the planet remaining bound to the Sun), and why?

A model shows the Sun (larger mass) and a planet (smaller mass). Gravity arrows point toward the Sun, and the planet has a motion arrow pointing forward along its orbit path. Which statement must be true based on the gravity arrows in the model?