I believe it is D, the reason being is because they form on their own, not from a living or dead organism. It can't be B because that is true, and the same for C. hope this helps, have an amazing day :)
The answer is that Both aid in the expansion and relaxation of lungs. Diaphragm and the rib muscles are vital in the breathing process. During inhalation the intercostal muscles contract, expanding the ribcage, the diaphragm contracts, pulling downwards to increase the volume of the chest, pressure inside the chest is lowered and air is sucked into the lungs. During exhalation the intercostal muscles relax, the ribcage drops inward and downwards, the diaphragm relaxes, moving back upwards, decreasing the volume of the chest, the pressure inside the chest increases and air is forced out.
A. It is present in all organisms and atmosphere.