Chemical Equilibrium Is Relatively Rare in Living Cells

Multiple Choice

Chemical equilibrium is relatively rare in living cells. Which of the following could be an example of a reaction at chemical equilibrium in a cell?

A) a reaction in which the free energy at equilibrium is higher than the energy content at any point away from equilibrium
B) a chemical reaction in which the entropy change in the reaction is just balanced by an opposite entropy change in the cell's surroundings
C) an endergonic reaction in an active metabolic pathway where the energy for that reaction is supplied only by heat from the environment
D) a chemical reaction in which both the reactants and products are not being produced or used in any active metabolic pathway at that time in the cell
E) no possibility of having chemical equilibrium in any living cell