A nurse reviews growth charts during well-child visits. Which child's growth pattern requires further investigation?

A. A 12-month-old whose weight increased from the 25th percentile to the 50th percentile: Gradual increases within normal percentiles reflect healthy growth and catch-up growth, which is generally not concerning when trends are consistent and proportional. B. A 6-month-old whose weight has remained at the 50th percentile since birth: Steady growth along the same percentile indicates appropriate weight gain and normal growth trajectory, requiring no further immediate investigation. C. A 2-year-old whose weight decreased from the 75th percentile to the 25th percentile over 6 months: A significant drop across percentiles in a short time suggests growth faltering, inadequate nutrition, chronic illness, or endocrine/metabolic issues. This pattern warrants further investigation to identify underlying causes and intervene promptly. D. A 4-year-old whose height and weight are both steadily at the 10th percentile and proportionate: Consistent growth along low but stable percentiles is generally normal if the child’s weight and height remain proportionate and developmental milestones are met, reflecting familial or constitutional growth patterns.