Insecticides pollute by harming non-target organisms

Steps:

• Define pollutant: A substance that adversely affects the environment or living organisms.
• Identify insecticide purpose: Chemicals designed to kill insects, often pests on crops.
• Assess broader impact: Insecticides can spread beyond targets, entering ecosystems like water and soil.
• Evaluate options: Select the one showing unintended environmental harm.

Why C is correct:

• Pollutants disrupt ecosystems by killing non-target species; insecticides broadly affect insects, reducing biodiversity per ecological impact laws.

Why the others are wrong:

• A: Insecticides target insects, not bacteria; they may indirectly affect microbes but don't increase them.
• B: They don't promote plant growth; some may harm aquatic plants via runoff.
• D: Insecticides spare plants by design, focusing on pests; plant death would contradict their use.

Final answer: C