During the reactivity of solids, two stages that may usually be identified are Nucleation of the product and its subsequent growth. When is nucleation facilitated?

• A. tWhen there is a structural similarity between the products
• B. tWhen there is structural similarity between the reactants
• C. tWhen there is structural dissimilarity between the product and the reactant
• D. tWhen there is structural similarity between the product and the reactant