Gravity. Specifically, the gravity of the Sun.
Unfortunately, you neglected to include the list of allowable choices that "follows" the question. Still, I know the answer. The force that keeps comets in closed orbits around the sun is the one that has the same effect on the planets; gravity. The only difference is that the orbits of the long-term comets are much more 'eccentric' (long and skinny) than those of the planets, so they have much shorter minimum distances from the sun, and much longer maximum distances, than planetary orbits have. So, the correct awnser is Gravity.
The solar system is found between the orbits of two planets, with the innermost known planet being Mercury and the outermost known planet being Neptune. The solar system also consists of other celestial bodies such as dwarf planets, moons, asteroids, and comets.
Asteroids are the celestial bodies found in between the spaces of the planets of the solar system. But comets are mysterious bodies that go far away from the known solar system and come back once very rarely.
Scientists do not consider celestial bodies like dwarf planets, moons, asteroids, and comets as major planets. Dwarf planets, such as Pluto and Eris, meet some criteria for being planets but not all, particularly in clearing their orbital zones. Moons are natural satellites orbiting planets, while asteroids and comets are smaller bodies that primarily reside in the asteroid belt or the outer solar system. These classifications are based on specific criteria established by the International Astronomical Union (IAU).
The Sun is a star at the center of the solar system, providing heat and light to the planets. The eight planets vary in size, composition, and distance from the Sun, with Mercury being the smallest planet closest to the Sun and Neptune being the farthest gas giant. Moons orbit many of the planets, with some having more than others. For example, Jupiter has the most moons in the solar system. Asteroids and comets also exist in the solar system, with asteroids being rocky and comets being icy.
The sun and its family of planets, dwarf planets, moons, asteroids, and comets make up the solar system. The sun is a star that holds about 99.8% of the solar system's mass and provides energy that sustains life on Earth. The planets orbit the sun in elliptical paths with the inner planets being rocky and the outer planets being gaseous. Each body in the solar system plays a unique role in the dynamics and balance of this celestial system.
There are three known asteroid belts (the Asteroid Belt, the Kuiper Belt, and the Oort Cloud) orbiting Sol, as well as many comets, planetoids, and other objects.
Comets are made of ice, dust, and rock. When a comet approaches the sun, the heat causes the ice to vaporize, creating a cloud called a coma and a tail. This process can make comets visible from Earth for a long time even though their ice is being continuously vaporized.
Natural satellites of the Sun are typically referred to as asteroids or comets that follow a path around the Sun. However, in the context of planets, Earth has one natural satellite (the Moon), while Mars has two small moons, Phobos and Deimos. Since the Sun itself does not have natural satellites in the same way planets do, it is more accurate to say that celestial bodies like asteroids and comets orbit the Sun rather than being its satellites.
The solar system consists of the sun and all the celestial objects that orbit around it, such as planets, moons, asteroids, and comets. It includes eight planets, with Earth being the third from the sun, and is located within the Milky Way galaxy.
All comets (there are over 3,500 known) have different time-scales for their appearances. These depend on the length of their orbits - some comets have extremely large orbits which take them from being 'close' to the earth to almost going out of our solar system. They appear because they come close enough to the Earth to be seen, and then they may take anything from a few years to hundreds of thousands of years beore they come back. The best-known comet is Halley's Comet which has a period of between 75 and 76 years between appearances.
A cloud of gas surrounding the nucleus.