At time t₁, the rates of the forward and reverse reactions for a gaseous reversible system are equal. Which of the following best characterizes the reaction mixture at t₁?
a) The reaction stops because both the forward and reverse rates become zero.
b) The equilibrium constant, K, for the reaction becomes zero at t1.
c) The concentrations of all species remain constant thereafter.
d) The concentrations of reactants and products are equal at this point.