A facility must ensure that dentures are ______ by the resident.

The correct choice emphasizes the importance of ensuring that dentures are retained by the resident. This focus on retention highlights the need for the resident to maintain possession of their dentures, which is crucial for their comfort and ability to function daily. Dentures are personal and can significantly affect a resident's quality of life, including their ability to eat, speak, and engage socially. By ensuring that the dentures are retained, the facility supports the resident's autonomy and dignity.

While options like cleaning, sanitizing, and safeguarding also relate to denture care, they do not address the fundamental need for the dentures to be in the resident's possession. Cleaning and sanitizing pertain primarily to hygiene and infection control, which are certainly critical aspects of denture management. Safeguarding focuses on protecting the dentures from loss or damage, which is important. However, the primary concern is that the resident should have their dentures available for their regular use, making retention the most appropriate choice in this context.