Pollution is change in physical, chemical or biological characters of our land and water that may be:

Options

A. Desirable and harmful to human
B. Desirable and useful to human
C. Undesirable and harmful to human
D. Undesirable and useful to human

Answer

**Step-by-Step Solution:**

1. **Define Pollution**: Pollution refers to the alteration in the physical, chemical, or biological characteristics of our environment, specifically land and water. This change can be caused by various substances known as pollutants.

2. **Identify Types of Pollutants**: Pollutants can be classified into two main categories:
- **Primary Pollutants**: These are directly emitted into the environment and include substances like nitrogen oxides (NO), carbon monoxide (CO), and carbon dioxide (CO2).
- **Secondary Pollutants**: These are formed when primary pollutants undergo chemical reactions in the atmosphere. Examples include sulfur trioxide (SO3) and peroxyacetyl nitrate (PANs).

3. **Impact of Pollution**: Pollution is generally considered undesirable as it poses significant health risks to humans. Contaminated air and water can lead to various diseases. For example:
- Dirty water can cause waterborne diseases such as cholera.
- Polluted air can lead to respiratory issues like asthma.

4. **Conclusion**: Given the harmful effects of pollution on human health and the environment, it is clear that pollution is undesirable. Therefore, the statement that pollution is a change in the physical, chemical, or biological characteristics of our land and water that is undesirable and harmful to humans is accurate.

5. **Final Answer**: The correct choice is that pollution is undesirable and harmful to humans.

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