Final answer:
The endotracheal tube is primarily intended to deliver oxygen to the lungs.
Step-by-step explanation:
The endotracheal tube is primarily intended to deliver oxygen to the lungs. It is a long, plastic tube that is placed in the respiratory system to bypass any obstructed area and allow air to reach the lungs. This tube is used during procedures such as intubation, where a person's respiratory system is blocked or injured, and artificial air supply is needed.