The tidel waves in the sea are primarily due to gravitational effect of

Options

A. earth on the sea
B. sun on the earth
C. earth on the moon
D. moon on the earth

Answer

To solve the question regarding the primary cause of tidal waves in the sea, we will analyze the gravitational effects of different celestial bodies on Earth.

### Step-by-Step Solution:

1. **Understanding Tidal Waves**: Tidal waves, or tides, are the periodic rise and fall of sea levels caused by the gravitational forces exerted by celestial bodies.

2. **Identifying the Options**: The options provided are:
- Option 1: Earth on the sea
- Option 2: Sun on the Earth
- Option 3: Earth on the Moon
- Option 4: Moon on the Earth

3. **Analyzing Gravitational Forces**:
- The gravitational force between two bodies is inversely proportional to the square of the distance between them. This means that the closer the two bodies are, the stronger the gravitational force they exert on each other.
- The distance between the Earth and the Moon is much smaller than the distance between the Earth and the Sun.

4. **Comparing Distances**:
- The average distance from the Earth to the Moon is about 384,400 km.
- The average distance from the Earth to the Sun is about 149.6 million km.
- Since the Moon is much closer to the Earth than the Sun, the gravitational pull of the Moon on the Earth is significantly stronger.

5. **Conclusion**: Given that the gravitational effect of the Moon on the Earth is the strongest due to the shorter distance, the primary cause of tidal waves in the sea is the gravitational effect of the Moon on the Earth.

6. **Final Answer**: Therefore, the correct answer is **Option 4: Moon on the Earth**.