Final answer:
The Earth's crust is mainly composed of oxygen and silicon, with oxygen making up about 50% of the crust's mass and silicon accounting for 28%. This pair of elements is the main component of silicate minerals, which constitute 90% of the crust.
Step-by-step explanation:
The Earth's crust is composed mainly of various minerals and elements, with two elements standing out in terms of abundance. The two elements that compose the majority of the Earth's crust are oxygen and silicon. Oxygen by itself accounts for roughly 50% of the mass of the crust when combined with other elements, and is particularly tied up with silicon to form various silicate minerals. On the other hand, silicon accounts for about 28% bymass of the crust, often found in compounds with oxygen, such as in the form of silicates which are the most prevalent minerals within the crust.
Given this information, among the pairs provided, the combination of silicon and oxygen is the predominant pair. The abundance of silicon and oxygen can be largely attributed to the extensive range of silicate minerals which make up around 90% of the Earth's crust, asserting their dominance in the Earth's composition. It is important to note that elements like iron and magnesium are also significant components, however, when compared to oxygen and silicon, their proportions are considerably less.