Question

which of the following processes is not primarily anthropogenic?
thinning of the ozone layer
air pollution
the greenhouse effect
increased carbon dioxide

Explanation:

The greenhouse effect is a natural process that warms the Earth's surface. While human activities have enhanced it (anthropogenic - enhanced greenhouse effect), it exists naturally. Thinning of the ozone layer is due to human - made chlorofluorocarbons. Air pollution is mainly caused by human industrial and vehicular emissions. Increased carbon dioxide is largely from human burning of fossil fuels.

Answer:

the greenhouse effect