Silicon is an important constituent of

Options

A. sand
B. atmosphere
C. plants
D. water bodies

Explanation

To solve the question "Silicon is an important constituent of," we can follow these steps:

### Step 1: Understand the Importance of Silicon
Silicon is a crucial element in the Earth's crust and is known for its abundance. It is the second most abundant element in the Earth's crust, making up about 25.7% of it.

**Hint:** Think about the natural abundance of elements in the Earth's crust.

### Step 2: Identify Common Forms of Silicon
Silicon primarily occurs in nature in the form of silicon dioxide (SiO2), commonly known as silica. It can also be found in various minerals and compounds, such as silicates.

**Hint:** Consider the common compounds and minerals that contain silicon.

### Step 3: List Substances Containing Silicon
Silicon is found in several natural materials, including:
- Clay
- Granite
- Quartz
- Sand

These materials are significant components of the Earth's crust.

**Hint:** Recall the geological materials that are prevalent in the Earth's crust.

### Step 4: Determine the Correct Answer
Among the options provided, sand is a significant constituent that contains silicon in the form of silicon dioxide (silica). Therefore, the correct answer to the question is sand.

**Hint:** Focus on which of the listed materials is primarily composed of silicon.

### Final Answer
Silicon is an important constituent of **sand**.

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