Which two elements are the most abundant in Earth's crust?

• A. Nitrogen and calcium
• B. Carbon and hydrogen
• C. Oxygen and silicon
• D. Iron and aluminum

Answer: (C)

Verified step by step guidance

1. Understand that the Earth's crust is composed of various elements, but some are much more abundant than others.
2. Recall that oxygen is the most abundant element in the Earth's crust, making up a significant portion of its composition.
3. Recognize that silicon is the second most abundant element in the Earth's crust, primarily found in silicate minerals.
4. Compare the given options and identify that 'Oxygen and silicon' are the two elements that are most abundant in the Earth's crust.
5. Note that other elements like nitrogen, calcium, carbon, hydrogen, iron, and aluminum are present but in smaller amounts compared to oxygen and silicon.