Final answer:
The lungs are indeed a source of water loss for the body, as they expel water through mucous secretions and the evaporation of water vapor.
Step-by-step explanation:
The statement that the lungs are a source of water loss for the body is true. The kidneys are indeed the main osmoregulatory organ, but the lungs also contribute to the body's water balance.
While you breathe, the lungs expel a small amount of water through mucous secretions and by evaporation of water vapor. This happens because the air in the lungs is humidified, which affects the water vapor pressure.
This process is part of the natural mechanism that maintains the pH of the blood and contributes to the removal of carbon dioxide, which is mixed with oxygen during respiration.