What must be maintained regarding the cleanliness of dentures by the resident?

The correct response emphasizes the importance of retaining dentures in a condition that preserves both their physical integrity and hygiene. Retaining dentures means ensuring they are properly stored when not in use and protected from damage that can occur through neglect or improper handling. This encompasses the need for not just cleanliness but also the proper maintenance that allows a resident to effectively use the dentures over the long term.

Maintaining dentures includes regular cleaning, but it also involves storing them in a safe, organized manner to prevent loss. Thus, retaining dentures not only addresses their cleanliness but also their accessibility and proper care, ensuring the resident can comfortably and confidently use them.

The other options focus on aspects like sanitation and cleanliness, which are essential parts of denture care but don't fully capture the holistic approach needed. Cleaning must be a component of retention, but simply mentioning cleanliness or sanitation does not encompass the broader responsibilities tied to proper denture management and the need for residents to have them easily accessible and in usable condition at all times.