The correct statement is: "The temperatures at which a substance changes phases indicate the relative strength of the forces between molecules in the substance."
This statement is correct because the temperature at which a substance changes phases (like melting or boiling) is influenced by the strength of the intermolecular forces. Stronger intermolecular forces typically result in higher melting and boiling points, as more energy (in the form of heat) is required to overcome these forces during a phase change.