A nurse is collecting data from an infant who is postoperative. Which of the following pain scales should the nurse use to evaluate the infant's pain level?

A. FACES: The FACES pain scale uses facial expressions that correspond to numeric ratings, but it is designed for children who are typically 3 years of age or older and can cognitively associate faces with levels of pain. Infants cannot reliably use this tool because they lack the developmental ability to self-report. B. FLACC: The FLACC scale (Face, Legs, Activity, Cry, Consolability) is validated for assessing pain in infants and young children who cannot verbally communicate. It evaluates observable behaviors such as facial grimacing, limb movement, activity level, crying, and consolability, providing an objective measure of pain intensity in nonverbal populations. C. Oucher: The Oucher scale is a self-report tool that uses photographs of children’s faces to represent pain intensity, appropriate for children around 3 to 12 years old. Infants cannot use this scale reliably because they cannot interpret or select images to indicate their pain level. D. Visual analog: The visual analog scale requires the child or adult to mark a point along a line to represent pain intensity. It relies on abstract reasoning and self-reporting and is not suitable for infants or nonverbal children, as they cannot understand or accurately use this method.