A nurse is assessing a 10-month-old infant. Which of the following findings should the nurse report to the provider?

A. Building a tower of three or four cubes is typically expected around 12 months of age, so inability at 10 months is within normal limits. B. Turning pages in a book is a skill that usually develops between 12–15 months, so a 10-month-old not performing this skill is not concerning. C. Imitating animal sounds generally emerges closer to 12 months, so this delay is within normal developmental range. D. Sitting steadily without support is expected by 8–9 months; inability to do so at 10 months suggests a delay in gross motor development and should be reported for further evaluation.