Which of the following helps in soil formation?

Options

A. Formation of rocks.
B. Arrangement of layers of sand.
C. Breaking down of rocks.
D. Arrangement of rocks.

Explanation

To determine which of the following helps in soil formation, we need to analyze the options provided:

1. **Formation of rocks**: This refers to the process where rocks are created from minerals and other geological processes. While rocks are important components of soil, their formation does not directly contribute to soil formation.

2. **Arrangement of layers of sand**: This option suggests that simply layering sand contributes to soil formation. However, soil is more complex than just layers of sand; it requires the breakdown of materials.

3. **Breaking down of rocks**: This is the process known as weathering, where rocks are broken down into smaller particles due to various factors such as wind, water, temperature changes, and biological activity. This process is crucial for soil formation as it transforms solid rock into smaller fragments that can mix with organic matter to create soil.

4. **Arrangement of rocks**: Similar to the arrangement of sand, simply arranging rocks does not contribute to the formation of soil. Soil formation requires the breakdown of these rocks rather than their arrangement.

After analyzing the options, the correct answer is:

**Breaking down of rocks** (Option 3) is the primary process that helps in soil formation.

### Step-by-Step Solution:
1. **Identify the options**: Look at the four options provided regarding soil formation.
2. **Understand what soil is**: Recognize that soil is the uppermost layer of the Earth, composed of loose fragments.
3. **Evaluate each option**:
- Formation of rocks does not contribute to soil formation.
- Arrangement of layers of sand is not sufficient for soil formation.
- Breaking down of rocks (weathering) is essential for creating soil.
- Arrangement of rocks does not aid in soil formation.
4. **Select the correct option**: Conclude that the breaking down of rocks is the correct answer.