For the reaction:
Which of the following graph is depicts the state of equilibrium:
In option (a) and (b), the concentration of reactants changes from zero to higher value. That is not true. The concentration of reactants always decreases.
The concentration of reactants decreases and concentration of products increases with time. After sometime the concentrations become constant which shows equilibrium.
In option (d), there is no region where concentration is constant showing equilibrium. So, option (d) is not correct.
Therefore, option (c) is correct.