What do comets and asteroids have in common? They are made of ice. They orbit the Sun. They are made of metal debris. They are at the center of the solar system.

They orbit the Sun.

Explanation:

Asteroids are small planetary bodies, too small to be classified as a planet. Asteroids are made up of rocky materials, and they orbit the sun. In our solar system, a vast number of asteroids exists together in the 'great asteroid belt' a region between the orbit of Mars and Jupiter. A comet is a ball of frozen gas, rocks and dusts, that travels around the sun in the solar system. Comets can be as big as a small town. When the orbit of a comet brings it close to the sun, it melts, leaving a trail of gas behind it. This trail of gas is the characteristic long tail of a wishing star seen in the sky in some clear night.

The common property of a comet and an asteroid is that they both travel around the sun in the solar system, just like every other planetary  body in the solar system.