Which of the following statements is incorrect about human eye?

Options

A. The diameter of the pupil is regulated by the muscle fibers of iris under autonomic nervous system.
B. The retina of human eyes has two types of cones which possess their own characteristic photopigments .
C. The Fovea is a thinned - out portion of the retina where only cones are densely packed .
D. Light induces dissociation of the retinal from opsin resulting in changes in the structure of the opsin.

Answer

To determine which statement is incorrect about the human eye, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Analyze Statement A**:
- The statement claims that the pupil diameter is regulated by the muscle fibers of the iris, which are under the control of the autonomic nervous system.
- **Evaluation**: This statement is correct. The iris does control the size of the pupil in response to light intensity, and this process is indeed regulated by the autonomic nervous system.

2. **Analyze Statement B**:
- The statement claims that there are two types of cones in the retina of the eye.
- **Evaluation**: This statement is incorrect. There are actually three types of cone cells in the human retina: red, blue, and green cones. These cones enable color vision through their different combinations.

3. **Analyze Statement C**:
- The statement claims that the fovea is a thinned-out portion of the retina where cones are densely packed.
- **Evaluation**: This statement is correct. The fovea is indeed the area of the retina with the highest concentration of cone cells, allowing for sharp vision.

4. **Analyze Statement D**:
- The statement claims that light dissociates retinal from opsin, causing a change in the structure of opsin.
- **Evaluation**: This statement is correct. The process described is part of the phototransduction pathway, where light causes a change in the structure of the opsin protein, leading to visual signal transduction.

### Conclusion:
The incorrect statement about the human eye is **Statement B**, which states that there are two types of cones in the retina. In reality, there are three types of cones (red, blue, and green).

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