The increased productivity of lakes and streams brought about by nutrient enrichment particularly by `PO_4^(3-) and NO_3^-` of detergents and fertilizers is known as

Options

A. Origin of life from living organism
B. eutrophication.
C. biomagnification
D. biochemical oxygen demand.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question is asking about the phenomenon that describes the increased productivity of lakes and streams due to nutrient enrichment, specifically from phosphorus (PO₄³⁻) and nitrate (NO₃⁻) derived from detergents and fertilizers.

2. **Identifying Key Terms**: The key terms in the question are "increased productivity," "nutrient enrichment," "phosphorus," and "nitrate." These terms indicate a process that leads to enhanced growth of aquatic plants and algae.

3. **Exploring Possible Answers**: The options provided are:
- Origin of life from living organism
- Eutrophication
- Biomagnification
- Biochemical oxygen demand

4. **Analyzing Each Option**:
- **Origin of life from living organism**: This refers to the beginning of life and is not related to nutrient enrichment.
- **Eutrophication**: This is the process where water bodies become overly enriched with nutrients, leading to excessive growth of algae and plants. This matches the description in the question.
- **Biomagnification**: This refers to the increasing concentration of toxins in organisms as one moves up the food chain, which is unrelated to nutrient enrichment.
- **Biochemical oxygen demand (BOD)**: This measures the amount of oxygen required to decompose organic matter in water, but does not directly describe the process of nutrient enrichment.

5. **Conclusion**: Based on the analysis, the correct answer is **Eutrophication**, as it directly relates to the increased productivity of lakes and streams due to nutrient enrichment from phosphorus and nitrate.

**Final Answer**: Eutrophication

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