What is a valid method for providing rescue breathing if the person's mouth is injured?

Mouth-to-mouth or mouth-to-nose is considered a valid method for providing rescue breathing, particularly in situations where the person's mouth is injured or otherwise inaccessible. This approach allows for effective ventilation and can help alleviate the life-threatening condition of respiratory arrest in the injured person.

In a scenario where a person's mouth is injured, using the mouth-to-nose method can circumvent the obstruction while still delivering the necessary air to the lungs, ensuring that oxygen reaches the circulatory system. This is crucial for maintaining oxygenation of vital organs until further help can arrive or until the individual begins to breathe independently.

The other options would not be as effective given the circumstances. Mouth-to-mouth is not viable if there is an injury that prevents access, and relying solely on chest compressions does not provide the necessary oxygen needed for survival during arrest unless an airway is clear and functioning. Therefore, the combination of both methods offers flexibility in saving a person’s life regardless of specific injuries to the mouth.