Mrs. Thompson, an 82-year-old woman, resides in a long-term care facility due to advanced dementia. She has a history of osteoarthritis and frequently experiences pain in her joints. Mrs. Thompson has limited verbal communication abilities and often relies on non-verbal cues to express discomfort. When using the PAINAID scale to assess Mrs. Thompson's pain level, which of the following non-verbal cues should the nurse primarily focus on?

A. Body movements: Body movements (e.g., guarding, restlessness) are an important observable domain on PAINAD and give useful information about discomfort, but they can also reflect agitation, mobility issues, or environment. B. Pain intensity: Pain intensity is a self-reported construct measured by numeric scales when the patient can self-report; in advanced dementia, self-report may be unreliable, so observational domains are used instead. C. Vocalizations: Negative vocalizations (moaning, groaning) are a PAINAD item and provide important clues, especially when verbal reports are absent, but they can be influenced by respiratory or emotional causes. D. Facial expressions: Facial expression is one of the five core PAINAD items (breathing, negative vocalization, facial expression, body language, consolability) and is often the single most consistent and sensitive nonverbal indicator of pain in people with advanced dementia - thus the primary focus when verbal report isn’t possible.