Final answer:
Tetracyclines can damage developing teeth and bone in children younger than 8 years of age.
Step-by-step explanation:
The priority reason for the nurse to consider questioning an order for tetracycline in a child younger than 8 years of age is that tetracyclines can damage developing teeth and bone in children of that age. Tetracyclines are known to cause permanent discoloration of developing teeth and can affect bone growth and development. Therefore, it is crucial to assess the age of the child and consider alternative antibiotics if possible.