The difference in the brightness of objects is due to difference in the____of light entering into our eyes.

Options

A. intensity
B. colour of light
C. speed
D. None of these

Explanation

To solve the question, "The difference in the brightness of objects is due to difference in the____of light entering into our eyes," we need to analyze the options provided and understand the concept of brightness in relation to light.

### Step-by-Step Solution:

1. **Understanding Brightness**: Brightness is the perception of how much light is coming from an object. It is a subjective experience that depends on how much light enters our eyes.

2. **Identifying Factors Affecting Brightness**: The brightness of an object can be influenced by several factors, including:
- The intensity of the light source (how much light is emitted).
- The color of the light (different colors can appear brighter or dimmer).
- The distance from the light source (how far away the object is).
- The surface properties of the object (how much light it reflects).

3. **Focusing on Intensity**: Among these factors, intensity is the most critical when discussing brightness. Intensity refers to the amount of light energy that passes through a unit area in a unit time. Higher intensity means more light is entering our eyes, leading to a perception of greater brightness.

4. **Conclusion**: Based on the understanding that brightness is primarily determined by the intensity of light, we can fill in the blank in the question. The correct answer is "intensity."

5. **Final Answer**: The difference in the brightness of objects is due to the difference in the **intensity** of light entering into our eyes.