Rusting iron is offered as an example of what important distinction?

1. Exergonic reactions are also called spontaneous, because they can occur without energy being added to the system. 2. Contrary to everyday use, a spontaneous reaction is not one that suddenly or quickly occurs. 3. The rusting of iron is a spontaneous reaction that occurs slowly, little by little, over time. 4. Rusting is slow because of its high activation energy, and the higher the activation energy the slower the reaction. 5. Endergonic reactions will not take place on their own without added free energy, so the first option is false. 6. Enzymes lower activation energy and never change the free energy change of a reaction. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 6 "Metabolism", section 6.2 Potential, Kinetic, Free, and Activation Energy_