Answer:
b. Icy objects that form a tail as they come close to the Sun
Step-by-step explanation:
Acording to NASA comets are cosmic snowballs made out of frozen gases, rock and dust, they usually are the size of a small town and contain water and organic compounds due to the collisions with Earth and other planets. When its orbit brings it close to the sun, it heats up, spewding dust and gases forming a tail that streches away from the sun, they also have a glowing head that is larger than most planets.
Considering this information we can conclude that the correct answer is b. Icy objects that form a tail as they come close to the Sun.
I hope you find this information useful and interesting! Good luck!