Question

collectively, the planets, moons, asteroids, and other objects that are orbiting the sun are referred to as a:
planetesimals system.
galaxy.
nebula.
planetary system.

Explanation:

• Planetesimals system: Planetesimals are small bodies from which a planet originated in the early stages of the solar system formation. This term does not refer to the collective of planets, moons, asteroids etc. orbiting the Sun.
• Galaxy: A galaxy is a huge system of stars, stellar remnants, interstellar gas, dust, and dark matter. Our solar system is part of the Milky Way galaxy, but the term galaxy is too broad for the description in the question.
• Nebula: A nebula is an interstellar cloud of dust, hydrogen, helium and other ionized gases. It is not the collective name for planets, moons etc. orbiting the Sun.
• Planetary system: A planetary system is a set of gravitationally bound non - stellar objects in orbit around a star or star system. The Sun is a star, and planets, moons, asteroids etc. orbiting it fit the definition of a planetary system.

Answer:

planetary system.