Answer:
Option d.
Step-by-step explanation:
The asteroid belt is a stellar disc which exists in between Mars and Jupiter's orbits which consists of a large no. of asteroids in our solar system.
the asteroids in the asteroid belt are formed from different regions and those asteroids with the similar chemical properties or compositions form a group and the different groups formed on these basis are distant from each other with some gap called as kirkwood gap. The gaps so formed are in resonance with Jupiter and are influenced by the strong gravitational force of Jupiter which renders them unstable in the region of resonance which prevents planet formation.