Which situation would most likely require an urgent call to a doctor?

An infection of an injury is the situation that would most likely require an urgent call to a doctor. Infections can escalate quickly and may lead to more serious health complications if not addressed promptly. This is particularly true if there are signs of swelling, redness, increased pain, or pus, which indicate that the body is fighting an infection that could spread.

In contrast, while a persistent headache can be concerning and potentially warrant medical attention, it does not always signify a medical emergency unless accompanied by other severe symptoms. A mild fever may also indicate an underlying issue but is often manageable without urgent medical intervention, particularly if it does not reach a high temperature or is not associated with other serious symptoms. A runny nose is typically a minor issue related to allergies or a mild cold and usually does not require a doctor's urgent care. Therefore, the need for urgent medical assessment is much more critical in the case of an infection of an injury.