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

To solve the question regarding the increased productivity of lakes and streams due to nutrient enrichment, we can follow these steps:

### Step 1: Understand the Question
The question is asking about a specific term that describes the increased productivity in aquatic ecosystems, particularly due to the enrichment of nutrients like phosphates (PO4^(3-)) and nitrates (NO3^-).

**Hint:** Look for terms related to nutrient enrichment in aquatic environments.

### Step 2: Identify Key Terms
The key terms in the question are "increased productivity," "lakes and streams," and "nutrient enrichment" by phosphates and nitrates.

**Hint:** Consider how nutrient enrichment affects aquatic ecosystems.

### Step 3: Recall Relevant Concepts
Nutrient enrichment in water bodies often leads to an increase in plant growth, particularly algae, which can result in a phenomenon known as "eutrophication." This process can lead to excessive growth of algae, which can deplete oxygen in the water and harm aquatic life.

**Hint:** Think about the ecological consequences of nutrient overload in water bodies.

### Step 4: Evaluate the Options
The options provided are:
1. Origin of life from living organisms
2. Eutrophication
3. Biomagnification
4. Biochemical oxygen demand

- **Origin of life from living organisms** does not relate to nutrient enrichment.
- **Eutrophication** directly refers to the process of nutrient enrichment leading to increased productivity.
- **Biomagnification** refers to the increase in concentration of toxic substances in the food chain, which is not relevant here.
- **Biochemical oxygen demand** measures the amount of oxygen required by bacteria during decomposition, which is also not the correct answer.

**Hint:** Eliminate options that do not relate to nutrient enrichment.

### Step 5: Conclusion
Based on the analysis, the correct answer is **Eutrophication**. This term specifically describes the process of increased productivity in aquatic ecosystems due to nutrient enrichment, particularly from sources like fertilizers and detergents.

**Final Answer:** The correct answer is **B. Eutrophication**.