Read the following statements.
A. A few rivers in India are like sewers.
B. Some cattle may die by feeding on plastic bags.
C. Installation of wastewater treatment plants have cleaned up most of the rivers in India.
D. Sludge is effectively utilised in the production of biogas.

Options

A. A,B and C
B. A,B and D
C. B, C and D
D. A,C and D

Answer

To analyze the given statements, we need to evaluate each one based on our understanding of environmental science and biology. Here’s a step-by-step breakdown of each statement:

### Step 1: Evaluate Statement A
**Statement A:** A few rivers in India are like sewers.
- **Analysis:** This statement is true. Many rivers in India are used as dumping grounds for sewage and waste, leading to severe pollution.

### Step 2: Evaluate Statement B
**Statement B:** Some cattle may die by feeding on plastic bags.
- **Analysis:** This statement is also true. Cattle often ingest plastic bags, which cannot be digested. This can lead to blockages in their digestive systems, causing health issues or death.

### Step 3: Evaluate Statement C
**Statement C:** Installation of wastewater treatment plants have cleaned up most of the rivers in India.
- **Analysis:** This statement is false. While wastewater treatment plants do help in treating sewage, many rivers remain polluted due to inadequate treatment facilities and improper waste disposal practices. Thus, the statement overstates the effectiveness of these plants.

### Step 4: Evaluate Statement D
**Statement D:** Sludge is effectively utilized in the production of biogas.
- **Analysis:** This statement is true. Sludge, which is a byproduct of wastewater treatment, can be used to produce biogas through anaerobic digestion. This biogas, primarily methane, can be used as a renewable energy source.

### Conclusion
Based on the evaluations:
- **Correct Statements:** A, B, and D are correct.
- **Incorrect Statement:** C is incorrect.

Thus, the final answer is that statements A, B, and D are correct.