Which of the following describes how oxygen can be delivered to a patient?

Oxygen can be delivered to a patient using various methods, which makes the third choice the most comprehensive and correct. These methods include a nasal cannula, which consists of two small prongs that fit inside the nostrils, and is often used for patients requiring low to moderate levels of supplemental oxygen. Additionally, oxygen can be delivered through a mask, which may provide higher concentrations of oxygen.

A concentrator is another viable option that can extract oxygen from the surrounding air and provide it to the patient, making it a valuable tool in many medical settings, especially for patients needing long-term oxygen therapy. This variety in delivery methods allows healthcare providers to tailor the oxygen therapy to meet each patient's specific needs effectively.

The other options are limited in scope. Delivering oxygen only through a mask does not encompass the complete range of delivery systems available, while using oral medication does not apply to oxygen, as oxygen is a gas, not a medication that can be administered orally. Lastly, stating that oxygen can only be delivered through a tank overlooks the existence of concentrators and other methods, which broadens the options available for effective oxygen therapy.