The correct answer is option 1: 4%. When we exhale, the air we release contains carbon dioxide. However, the percentage of carbon dioxide in our exhaled air is relatively low compared to the amount of other gases, such as nitrogen and oxygen. The average carbon dioxide content in exhaled breath is approximately 4%. This means that for every 100 molecules of gas in our breath, only about 4 molecules are carbon dioxide. It is important to note that the concentration of carbon dioxide in exhaled air can vary based on factors such as metabolic rate, physical activity, and overall health.