The blue colour of the water of the sea is due to :

Options

A. the presence of algae and other plants found in water
B. reflection of sky in water
C. scattering of light
D. absorption of light by the sea

Explanation

To determine the reason behind the blue color of the sea water, we can analyze the options provided and apply our understanding of light scattering.

### Step-by-Step Solution:

1. **Understanding Light and Color**:
- White light consists of multiple colors, which can be remembered using the acronym VIBGYOR (Violet, Indigo, Blue, Green, Yellow, Orange, Red). Each color has a different wavelength.

2. **Scattering of Light**:
- The phenomenon of scattering occurs when light interacts with particles in a medium. The amount of scattering is inversely proportional to the fourth power of the wavelength (λ). This means shorter wavelengths scatter more than longer wavelengths.

3. **Identifying Relevant Colors**:
- Among the colors in white light, violet, indigo, and blue have shorter wavelengths compared to other colors like green, yellow, orange, and red. Therefore, they will scatter more effectively.

4. **Analyzing the Options**:
- **Option 1**: Reflection of blue light by impurities in the sea water - This does not explain the inherent color of the water itself.
- **Option 2**: Reflection of blue light by sea water - This is not the primary reason for the blue color.
- **Option 3**: Scattering of blue light by sea particles - This aligns with our understanding of light scattering.
- **Option 4**: Absorption of other colors except blue by the water molecules - While water does absorb some colors, the primary reason for the blue appearance is scattering.

5. **Conclusion**:
- Based on the analysis, the correct answer is **Option 3: Scattering of blue light by sea particles**. This scattering is what gives the sea its blue color.

### Final Answer:
The blue color of the water of the sea is due to the **scattering of blue light by sea particles**.

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