Dark adaptation is the process by which the eye becomes progressively more sensitive in low light. Several events drive it:
$\bullet$ Pupil dilates (mydriasis): sympathetic tone and reduced light input cause the dilator pupillae to widen the pupil, increasing the photon flux reaching the retina - an early effect.
$\bullet$ Visual pigment regeneration: in the visual (retinoid) cycle, vitamin A / retinol is converted to $11$-cis retinal, which combines with opsin to rebuild rhodopsin. Stored rhodopsin makes the rods exquisitely sensitive.
$\bullet$ Rise in retinal sensitivity: with abundant rhodopsin and a shift to scotopic (rod) vision, the threshold for light detection falls dramatically.
The statement that rhodopsin/opsin breaks down to photopsin is wrong for the dark phase: pigment bleaching (rhodopsin $\to$ opsin $+$ all-trans retinal) is a property of bright light, and photopsin denotes cone pigments, not a rod-bleaching product. So that option is false.
\[\boxed{\text{Dark room}\Rightarrow \text{mydriasis} + \text{rhodopsin regeneration} + \uparrow\text{sensitivity}}\]