Fill in the blanks with most appropriate option.
Although a number of objects, such as kites, birds, aeroplanes move in space, but their shadow is not seen on the earth. This is due to the reason that the (i) , the region of complete (ii) is not able to reach the earth. The region of partial (iii) , that is the (iv) reaching the earth is too large and too faint to be visible to us.

Options

A. (i)- Penumbra, (ii) -Darkness, (iii) - Brightness, (iv) - Umbra
B. (i)-Penumbra, (ii) - Brightness, (iii) - Darkness, (iv) Umbra
C. (i) - Umbra, (ii) Darkness, (iii)-Brightness, (iv) - Penumbra
D. (i) - Umbra, (ii) - Brightness, (iii) - Darkness, (iv) - Penumbra

Explanation

To fill in the blanks in the given statement, we need to understand the concepts of shadows and light. Here's the step-by-step solution:

1. **Understanding the context**: The question discusses why shadows of objects moving in space (like kites, birds, and aeroplanes) are not seen on Earth. This relates to the concepts of umbra and penumbra in shadow formation.

2. **First blank**: The first blank requires a term that describes a region of complete darkness. This is known as the "umbra."
- **Answer**: Umbra

3. **Second blank**: The second blank also requires a term that describes what the umbra represents. Since it is a region of complete darkness, the appropriate word is "darkness."
- **Answer**: Darkness

4. **Third blank**: The third blank refers to a region that is not completely dark but partially illuminated. This region is known as the "penumbra."
- **Answer**: Penumbra

5. **Fourth blank**: The fourth blank needs a term that describes the type of light that reaches the Earth from the penumbra. Since the penumbra is a region of partial light, the correct term is "brightness."
- **Answer**: Brightness

Now, putting it all together, we have:

"Although a number of objects, such as kites, birds, aeroplanes move in space, but their shadow is not seen on the earth. This is due to the reason that the **(i) Umbra**, the region of complete **(ii) Darkness** is not able to reach the earth. The region of partial **(iii) Penumbra**, that is the **(iv) Brightness** reaching the earth is too large and too faint to be visible to us."