Why is it important to name "air" as part of the system?

Your respiratory system is the network of organs and tissues that help you breathe. This system enables your body soak up oxygen from the air so your organs can work. It also cleans waste gases, which includes carbon dioxide, from your blood. Common troubles encompass allergies, illnesses or infections.

the answer would be c

in cartography, a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level. a contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes.

explanation: