The correct statement that compares synthesis and decomposition reactions is:
Synthesis and decomposition reactions are opposites of each other. Synthesis reactions are in the form A + B → AB, while decomposition reactions are in the form AB → A + B.
This reflects the relationship accurately: synthesis reactions involve combining two or more reactants to form a single product (A + B → AB), while decomposition reactions involve breaking down a single reactant into two or more products (AB → A + B).