A. 4,3,2.
When you add a coefficient it multiplies what it is connected to in math. So when you have 4 Fe, that means there are 4 Fe atoms. When you add a 3 in front of O₂, that will make 6 O atoms. Since the product (right) side is Fe₂0₃, and you need to add a 2 in front of it to balance the equation. After adding the coefficients you will have 4 Fe atoms and 6 O atoms on both the reactants (left) side and the products (right side. Hope this helps!
