Balance the following chemical equation (if necessary): Ca(s) + O₂(g) → CaO(s).
A) 2Ca(s) + O₂(g) → 2CaO(s)
B) Ca(s) + 1/2O₂(g) → CaO(s)
C) Ca(s) + O₂(g) → 2CaO(s)
D) 2Ca(s) + 1/2O₂(g) → CaO(s)