Final answer:
Global warming is mainly caused by an increase in CO₂ levels in the atmosphere due to human activities such as burning fossil fuels and deforestation.
Therefore, the correct answer is: option C). increase in co₂ levels
Step-by-step explanation:
Climate change refers to long-term shifts in temperatures and weather patterns. These shifts may be natural, but since the 1800s, human activities have been the main driver of climate change, primarily due to the burning of fossil fuels (like coal, oil, and gas), which produces heat-trapping gases.
The main cause of global warming is the increase in CO₂ levels in the atmosphere. This is primarily due to human activities such as burning of fossil fuels and deforestation.
When fossil fuels are burned, carbon dioxide is released into the air, contributing to the greenhouse effect and trapping heat in the Earth's atmosphere.
Other factors, such as an increase in H₂O levels (water vapor) and increase in N₂O levels (nitrous oxide), also contribute to global warming, but CO₂ is considered the most significant greenhouse gas responsible for the current warming trend.