Answer:
The excretory system helps the respiratory system by removing carbon dioxide that is produced during respiration (third option).
Explanation:
The lungs are in charge of the breathing process, being the main organ of the respiratory system. Each lung is considered an excretory organ —belonging to the excretory system— since it is capable of eliminating the carbon dioxide (CO₂) produced by the metabolism during expiration.
As a result of the gaseous exchange, the oxygen entering the lungs through the inhaled air passes into the blood, while the CO₂ is removed from the blood. This CO₂ is removed during expiration, which makes the lungs part of the excretory system.
The other options are not correct because:
- The excretory system does not introduce more oxygen into the lungs.
- The circulation of blood in and out of the lungs is a function of the circulatory system.
- Urine is not produced by breathing.
