Iris/Eye lids of eye acts/ act as diaphragm of eye.

Explanation

### Step-by-Step Solution:

1. **Understanding the Function of the Iris and Eyelids**:
- The iris is a thin, circular structure in the eye that controls the diameter and size of the pupil. It regulates the amount of light that enters the eye.
- Eyelids serve to protect the eye from foreign particles and excessive light, and they also help in spreading tears over the surface of the eye.

2. **Comparison to a Diaphragm**:
- A diaphragm is a structure that can expand and contract to control the passage of light or air. In photography, for example, the diaphragm of a camera lens adjusts to control the amount of light hitting the sensor.
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