Final answer:
Option A. Rapid growth and ulceration of an infantile hemangioma should raise concern and may necessitate medical intervention, due to the increased risk of complications such as infection, pain, and potential scarring.
Step-by-step explanation:
Infantile hemangiomas that should raise concern and might require intervention include those that exhibit rapid growth and ulceration. These symptoms can indicate an increased risk for complications and should prompt further evaluation by a healthcare professional. Rapid growth of a hemangioma can lead to issues with surrounding tissues, while ulceration can result in pain, infection, and potential scarring.
In contrast, a pale color and reduced blood flow in a hemangioma might not necessarily imply immediate concern, but still warrants monitoring. Complete regression within a month is unusual and might require further investigation to rule out other conditions. On the other hand, having no change in appearance is typically not worrisome, especially if a hemangioma is small and not causing any complications.