Final answer:
Global warming occurs primarily in the Troposphere (I), the beneficial ozone layer is in the Stratosphere (II), and most oxygen is found in the Troposphere (I) as well.
Step-by-step explanation:
The phenomenon causing global warming primarily occurs in the Troposphere (I) of the atmosphere.
The beneficial ozone layer is located in the Stratosphere (II) of the atmosphere.
Most oxygen is found in the Troposphere (I) of the atmosphere.
Learn more about Atmospheric Layers