The ministry of Environment and Forest has initiated Ganga action plan and Yamuna action plan
(i) To save these major rivers of our country from pollution
(ii) It is proposed to build a large number of sewage treatment plants
(iii) Under these plans, only treated sewage may be discharged in the river

Options

A. (i) and (ii) are correct
B. (ii) and (iii) are correct
C. (i) and (iii) are correct
D. All are correct.

Answer

### Step-by-Step Solution:

1. **Understanding the Initiatives**: The Ministry of Environment and Forest has initiated the Ganga Action Plan and Yamuna Action Plan. These plans aim to address the pollution in these major rivers in India.

2. **Objective of the Plans**: The primary objective of these plans is to save the Ganga and Yamuna rivers from pollution. This is crucial as these rivers are significant for both ecological balance and human life.

3. **Sewage Treatment Plants**: One of the key proposals under these plans is to build a large number of sewage treatment plants. These plants are essential for treating the sewage before it is discharged into the rivers, thus reducing the pollution levels.

4. **Discharge of Treated Sewage**: Another important aspect of these plans is that only treated sewage may be discharged into the rivers. This means that any sewage that enters the rivers must first go through treatment processes to ensure that it meets safety and quality standards.

5. **Evaluating the Statements**:
- Statement (i): To save these major rivers from pollution - **True**.
- Statement (ii): It is proposed to build a large number of sewage treatment plants - **True**.
- Statement (iii): Under these plans, only treated sewage may be discharged in the river - **True**.

6. **Conclusion**: Since all three statements are correct, the answer to the question is that all the statements (i, ii, and iii) are true. Therefore, the correct option is option 4: all are correct.