What primarily composes the outer layer of Uranus?

The outer layer of Uranus is primarily composed of hydrogen and helium. These two elements make up the bulk of the gas giant's atmosphere, which is characteristic of the outer planets in our solar system. Hydrogen is the most abundant element and exists in molecular form, while helium is the second most abundant, contributing to the overall gaseous composition of the planet.

The significance of hydrogen and helium in the context of Uranus lies in their roles in planetary formation and characteristics. As a gas giant, Uranus has a thick atmosphere that retains a multitude of gases, leading to its low density. This composition is similar to other gas giants, such as Jupiter and Saturn, indicating a trend in the formation processes of large planetary bodies in the outer solar system.

While other options present different materials, they do not accurately represent the primary components of Uranus’s outer layer, which is predominantly hydrogen and helium.