Final answer:
The passage defines the Aqua Lung's purpose and operation in scuba diving and credits its inventors, which best aligns with option D that the passage defines the term and shows its uses.
Step-by-step explanation:
The passage provided describes the Aqua Lung, which is a type of underwater breathing apparatus used in scuba diving. It outlines how the equipment works by supplying breathing gas from a cylinder through a regulator and into the diver's mouth, then releasing the used gas into the water.
The passage acknowledges Emile Gagnan and Jacque-Yves Cousteau as the creators of the Aqua Lung and briefly mentions its benefit in allowing divers to explore deeper parts of the ocean safely. Given these points, the best description of how the passage is organized is option D, which states the passage defines the term Aqua Lung and shows its uses.