Answer:

When we inhale, we breathe in air into our lungs. This air contains various gases, including oxygen, nitrogen, carbon dioxide, and trace amounts of other gases. When we exhale, we release air from our lungs, and the composition of this exhaled air is different from the inhaled air.

Air Composition:
- Inhaled air: When we inhale, the air we breathe in contains approximately 21% oxygen, 78% nitrogen, and trace amounts of other gases, including carbon dioxide.
- Exhaled air: When we exhale, the air we breathe out contains approximately 16% oxygen, 79% nitrogen, and an increased amount of carbon dioxide, which is around 4%.

Process of Respiration:
- When we inhale, the diaphragm and intercostal muscles contract, causing the chest cavity to expand. This expansion creates a pressure difference, and air rushes into the lungs through the nose or mouth.
- In the lungs, oxygen from the inhaled air is transferred to the bloodstream, where it binds to hemoglobin in red blood cells. This oxygen-rich blood is then transported to various organs and tissues in the body to support cellular respiration.
- Cellular respiration is the process by which cells use oxygen to break down glucose and produce energy in the form of ATP (adenosine triphosphate). As a result of this process, carbon dioxide is produced as a waste product.
- The carbon dioxide produced during cellular respiration diffuses out of the cells and into the bloodstream, where it is transported back to the lungs.
- During exhalation, the diaphragm and intercostal muscles relax, causing the chest cavity to decrease in size. This decrease in size creates a pressure difference, and air is expelled from the lungs through the nose or mouth.

Carbon Dioxide in Exhaled Air:
- The increased amount of carbon dioxide in the exhaled air is a result of the waste product produced during cellular respiration.
- The carbon dioxide diffuses from the bloodstream into the alveoli, which are tiny air sacs in the lungs where gas exchange occurs.
- From the alveoli, the carbon dioxide is then expelled during exhalation, along with the remaining oxygen and nitrogen.

Therefore, the correct answer is option 'D' - when we exhale, we release air that has more carbon dioxide than inhaled air.

When we exhale, we breathe out less oxygen but more carbon dioxide than we inhale. The carbon we breathe out as carbon dioxide comes from the carbon in the food we eat.