Which of the following statements about sources of water pollution is correct?

• A. A source of water pollution must involve the introduction of a chemical substance into the water.
• B. Only physical changes, such as temperature increase, can be considered sources of water pollution.
• C. Water pollution sources are limited to biological contaminants and do not include chemicals.
• D. A source of water pollution cannot include any chemical substances.

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the definition of water pollution. Water pollution occurs when harmful substances contaminate a water body, degrading water quality and affecting living organisms.
2. Step 2: Recognize that sources of water pollution can be chemical, physical, or biological. Chemical substances such as pesticides, heavy metals, and industrial waste are common pollutants.
3. Step 3: Note that physical changes, like temperature increases (thermal pollution), can also negatively impact aquatic ecosystems, so physical changes are indeed sources of water pollution.
4. Step 4: Understand that biological contaminants, such as bacteria and viruses, are also sources of water pollution, but pollution is not limited to biological contaminants alone.
5. Step 5: Conclude that a correct statement about sources of water pollution must acknowledge that chemical substances can be introduced into water and cause pollution, so the statement claiming that only chemical substances cause pollution is the most accurate among the options.