Final answer:
The solar system formed from a nebula composed of hydrogen and helium gases, supplemented by heavier elements from supernova explosions. This nebula contracted and heated up, forming the Sun and planetesimals that led to the planets. The composition varies from metal-rich inner planets to icy outer bodies. The correct option is D.
Step-by-step explanation:
The material from which our solar system formed is best described as a nebula made mostly of hydrogen and helium gas, but enriched in heavier elements from supernova explosions. This description aligns with the information that our solar system originated approximately 4.5 billion years ago from a rotating cloud of vapor and dust, which is referred to as the solar nebula.
As the solar nebula contracted under gravity, it became hotter and denser, ultimately leading to the formation of the Sun at its core and the development of planetesimals in the surrounding disk. These planetesimals are the building blocks of the planets.
The condensation in the disk and accretion of infalling materials allowed the differentiation of planets, with giant planets like Jupiter and Saturn capturing more of the nebula's gas due to their larger gravitational fields. Consequently, the composition of our solar system, from the rocky inner planets to the icy bodies in the Kuiper belt and Oort cloud, reflects the distribution of materials within the early solar nebula.
Hence, Option D is correct.