Which of the following is the most common source of contamination for freshwater resources?

• A. Thermal pollution from power plants
• B. Runoff from agricultural activities
• C. Volcanic eruptions
• D. Atmospheric dust

Answer: (B)

Verified step by step guidance

1. Understand the context: Freshwater contamination refers to the introduction of harmful substances into lakes, rivers, and groundwater, which can affect water quality and ecosystem health.
2. Analyze each option by considering common sources of freshwater pollution: Thermal pollution from power plants involves heated water discharge, which affects temperature but is less about chemical contamination.
3. Volcanic eruptions can introduce minerals and gases into water but are relatively rare and localized events, so they are not the most common source.
4. Atmospheric dust can settle into water bodies, but its impact is generally less significant compared to other sources.
5. Runoff from agricultural activities often carries fertilizers, pesticides, and animal waste into freshwater systems, making it the most frequent and widespread source of contamination.