The two most abundant elements in Earth's core are A. silicon and oxygen B. iron and magnesium C. nickel and silicon D. iron and nickel

D. iron and nickel

Explanation:

In the earth's core the two most abundant elements that can be found are different than those that are abundant in the earth's crust, in the core you can find almost 86% of iron and then closely followed by Silicon and Nickel with almost 15% between the two of them, scientists vary on the concentration of each, so from the options the one that makes the most sense would be Iron and another one of silicon or nickel, since the only one that combines iron and one of those is D, that should be correct.