Primary cause of global warming: greenhouse gas emissions

Steps:

• Recall that global warming results from increased greenhouse gases trapping heat in Earth's atmosphere.
• Evaluate each option for its link to greenhouse gas production.
• Identify emissions from fossil fuels as the dominant source of carbon dioxide (CO2).
• Confirm this by noting fossil fuel burning accounts for over 75% of human-caused CO2 emissions.

Why C is correct:

• Burning fossil fuels releases CO2, the main greenhouse gas, directly contributing to the enhanced greenhouse effect that warms the planet.

Why the others are wrong:

• A: Ocean plastics harm marine life but do not emit significant greenhouse gases.
• B: Pesticides cause soil and water contamination, not direct atmospheric warming.
• D: Sewage pollutes water sources, leading to eutrophication, but has minimal impact on global temperatures.

Final answer: C