Answer:
D. sulfur oxides from factories
Explanation:
This does not naturally occur, only if there is a factory. These other things happen on their own in nature but sulfur from factories relies on other factors down on earth.
sulfur oxides from factories is not a naturally occurring part of Earth's atmosphere.
EPA’s national ambient air quality standards for SO2 are designed to protect against exposure to the entire group of sulfur oxides (SOx). SO2 is the component of greatest concern and is used as the indicator for the larger group of gaseous sulfur oxides (SOx).
Other gaseous SOx (such as SO3) is found in the atmosphere at concentrations much lower than SO2.
Thus, sulfur oxides from factories is not a naturally occurring part of Earth's atmosphere.
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