Question

lo 4.2. what is the main organ of the respiratory system?
kidneys
lungs
brain
liver
heart

Explanation:

The respiratory system's main function is gas exchange (taking in oxygen and expelling carbon dioxide). The lungs are the primary organs where this gas - exchange process (involving alveoli) occurs. Kidneys are part of the excretory system (filter blood and form urine). The brain is part of the nervous system (controls body functions). The liver is part of the digestive and detoxification systems. The heart is part of the circulatory system (pumps blood).

Answer:

Lungs