Which elements are primarily found in the Earth's mantle?

The Earth's mantle is composed predominantly of silicate minerals, which are characterized by the presence of silicon and oxygen as key components. The correct choice, which includes silicon and oxygen, accurately reflects this composition. In addition to silicon and oxygen, iron and magnesium are also significant elements in the mantle, contributing to the structure and properties of the mantle's rocks. This combination of elements plays a crucial role in the geophysical and chemical processes that occur within the mantle, such as the convection currents that drive plate tectonics.

In contrast, other options mention elements that are not prevalent in the mantle. For instance, while oxygen is indeed abundant, hydrogen and the combination of carbon and nitrogen are not major constituents of the mantle. Iron and sulfur are found in the Earth, but sulfur is not a primary component of the mantle compared to silicon, oxygen, iron, and magnesium, which fundamentally define its composition. Therefore, the inclusion of silicon, oxygen, iron, and magnesium in the correct choice reflects the actual makeup of the Earth's mantle accurately.