Final answer:
The parts of Earth where life exists, encompassing air, water, and soil, are known as the Biosphere. Therefore, the correct option is A.
Step-by-step explanation:
The name given to the parts of the Earth's air, water, and soil where organisms are found is A) Biosphere. The biosphere consists of all the regions of Earth where life exists, ranging approximately 11,000 meters below sea level up to 15,000 meters above sea level. It includes parts of the lithosphere, hydrosphere, and atmosphere, enveloping the areas where land plants, freshwater and marine plants, animals, protists, fungi, and various other life forms exist.