What describes reversible chemical reactions?

Reversible chemical reactions are characterized by the ability of the reactants to revert back into products and vice versa. This means that the forward reaction (where reactants are converted into products) can be followed by a reverse reaction (where products are converted back into reactants).

In the context of this concept, the correct answer emphasizes that in a reversible reaction, the system can achieve a state of dynamic equilibrium where reactants and products are constantly interconverting, but their concentrations remain stable over time. This is critical in many biological, chemical, and environmental processes.

The other options do not accurately capture the essence of reversible reactions. For instance, the notion that products are consumed completely or that only products are formed misrepresents the fundamental dynamic of a reversible reaction, where both reactants and products are present and capable of reacting in both directions.