A nurse is caring for a 6-month-old infant who has gastroenteritis. Which of the following findings should the nurse identify as a manifestation of severe dehydration?

The correct answer is B: Sunken anterior fontanel. Severe dehydration in infants can lead to a sunken anterior fontanel due to decreased fluid volume in the body. The fontanel is a soft spot on the baby's head where the skull bones haven't yet fused, and its sunken appearance indicates significant fluid loss. Other options (A) Weight loss of 5%, (C) Produces tears when crying, and (D) Capillary refill time 3 seconds are important assessments in dehydration but are not specific to severe dehydration. Weight loss can occur in mild to moderate dehydration, tear production is not a reliable indicator of dehydration severity, and a capillary refill time of 3 seconds is within the normal range. Therefore, the sunken anterior fontanel is the most indicative of severe dehydration in this scenario.