Final answer:
The reaction to form Fe2O3 requires 2 atoms of iron as reactants.
Step-by-step explanation:
The question is asking how many atoms of iron are needed as reactants in a chemical reaction that produces iron(III) oxide (Fe2O3) as the product. The balanced chemical reaction for the formation of Fe2O3 is:
2 Fe(s) + 3/2 O2(g) → Fe2O3(s)
From this balanced equation, we can see that 2 atoms of iron (Fe) are needed as reactants to produce 1 molecule of Fe2O3. Therefore, the answer is d. 2.