Chemical Kinetics And Nuclear Chemistry

For a reversible reaction $R \rightleftharpoons P$, at constant temperature, both the forward and the backward reactions are first order elementary reactions with rate constants $k_{{f}}$ and $k_{{b}}$, respectively. At time zero, the concentration of $R$ is $[R]_0$ and the concentration of $P$ is zero. At any given time, $[R]$ and $[P]$ are the concentrations of $R$ and $P$, respectively. If $k_{{b}} = 4k_{{f}}$, the correct graphical representation of the reaction is