Which part allows light to enter the eye ?

Options

A. Retina
B. Cornea
C. Iris
D. pupil

Answer

To determine which part of the eye allows light to enter, we can analyze the given options step by step:

1. **Understand the Function of Each Part**:
- **Retina**: The retina is the inner layer of the eye where the image is formed. It does not allow light to enter; instead, it processes the light that has already entered.
- **Cornea**: The cornea is the transparent front part of the eye. It helps to focus light but does not directly allow light to enter. It mainly refracts (bends) the light rays.
- **Iris**: The iris is the colored part of the eye that surrounds the pupil. Its main function is to control the size of the pupil, thereby regulating the amount of light that enters the eye.
- **Pupil**: The pupil is the opening in the center of the iris. It is the part of the eye that directly allows light to enter.

2. **Identify the Correct Answer**:
- Among the options, the pupil is the only part that directly allows light to enter the eye. The other parts either help in focusing or regulating the light but do not serve as the entry point.

3. **Conclusion**:
- The part of the eye that allows light to enter is the **pupil**.

### Final Answer:
The part that allows light to enter the eye is the **pupil**.