Final answer:
Residents should be repositioned every two hours by the CNA to prevent pressure ulcers and maintain proper circulation.
Step-by-step explanation:
The Certified Nursing Assistant (CNA) is responsible for many aspects of patient care in a healthcare setting, one of which includes ensuring that residents are properly repositioned to prevent pressure ulcers and maintain proper circulation. According to standard healthcare practices, residents should typically be repositioned every two hours. This interval is vital to prevent the development of bedsores and to ensure the comfort and health of residents who may not be able to change positions on their own.