Read the given paragraph.
X prevents soil erosion occurring due to flowing water on hills whereas Y prevents soil erosion occurring due to flowing water in plains.
Identify X and Y and select the incorrect option regarding them.

Options

A. X is an agricultural practice wherein slopes of hills are cut into graduated terrace that are used for growing crops.
B. Y is built along river banks and prevents soil erosion by floods
C. X is terrace farming and Y is deforestation.
D. The amount of soil lost is less in X as the soil eroded from one step is deposited on the next step.

Explanation

To solve the question, we need to identify what X and Y refer to in the context of preventing soil erosion in different geographical areas and then find the incorrect option regarding them.

### Step-by-Step Solution:

1. **Identify X**: The paragraph states that X prevents soil erosion occurring due to flowing water on hills. This is typically achieved through a practice called **terrace farming**. In terrace farming, the slopes of hills are cut into graduated terraces. This method helps to slow down water runoff and allows soil to remain in place, thus preventing erosion.

2. **Identify Y**: The paragraph mentions that Y prevents soil erosion occurring due to flowing water in plains. This is commonly done using **embankments**. Embankments are structures built along river banks to prevent flooding and soil erosion in flat areas. They help to contain water during floods, protecting the soil and crops in the plains.

3. **Evaluate Options**: Now, we need to analyze the provided options regarding X and Y to find the incorrect one:
- Option 1 states that X is an agricultural practice (terrace farming), which is correct.
- Option 2 states that Y is built along river banks to prevent soil erosion by floods, which is also correct.
- Option 3 states that X is terrace farming and Y is deforestation, which is incorrect because Y should refer to embankments, not deforestation.
- Option 4 states that the amount of soil lost is less in X because the soil eroded from one step is deposited on the next step, which is correct.

4. **Conclusion**: Therefore, the incorrect option regarding X and Y is the one that states Y is deforestation.

### Final Answer:
- X is terrace farming.
- Y is embankments.
- The incorrect option is that Y is deforestation.