Which one of these is an example of displacement reaction?

• A. Fe(s) + CuSO4(aq) = FeSO4(aq) + Cu(s)
• B. 2FeSO4(s) = Fe2O3(s) + SO2(g) + SO3(g)
• C. CaO(s) + H2O (1) = Ca(OH)2 (aq)
• D. C(s) + O2(g) = CO2 (g)