Final answer:
Damage to a developing permanent tooth after primary tooth intrusion typically becomes evident when the permanent tooth has erupted, allowing for full assessment of its position and health.
Step-by-step explanation:
When assessing if damage is done to a developing permanent tooth after the primary tooth is intruded, such damage is generally not evident immediately. It can become apparent when the permanent tooth has erupted. This is the stage at which the position and health of the permanent tooth can be fully assessed.
The effects of an intrusion or other injury to the primary tooth may not impact the development of the permanent tooth but they can influence its eruption pattern or final position. Since the development of the permanent tooth occurs over several years and beneath the gum line any disruption in this process caused by earlier injury likely won't be visible until the tooth emerges and is fully visible. Therefore the answer is d) When the permanent tooth has erupted.