If "I' is the intensity of absorbed light and 'C' is the concentration of AB for the photochemical process $\mathrm{AB}+\mathrm{hv}⟶{\mathrm{AB}}^{\ast }$, the rate of formation of AB* is directly proportional to

Directly proportional to Cl is the rate at which AB forms.

The rate-determining step is stated as $\mathrm{r}=\mathrm{K}\cdot {\mathrm{I}}_{\mathrm{abs}}$for all photo primary processes in pure species.

The solution state, however, $\mathrm{r}={\mathrm{KI}}_{\mathrm{abs}}\cdot \mathrm{C}$.

As a result, choice D is the right response.