In mammalian eye, the 'fovea' is the centre of the visual field, where

Options

A. More rods than cones are found
B. High density of cones occur, but has no rods
C. The optic nerve leaves the eye
D. Only rods are present

Answer

### Step-by-Step Solution:

1. **Understanding the Structure of the Mammalian Eye**:
- The mammalian eye consists of three main layers: the fibrous tunic, the vascular tunic, and the neurosensory layer.
- The fibrous tunic includes the sclera (the white part of the eye) and the cornea (the transparent front part of the eye).

2. **Identifying the Layers of the Eye**:
- The vascular tunic consists of the choroid, ciliary body, and iris.
- The neurosensory layer, also known as the retina, contains the photoreceptor cells (rods and cones).

3. **Understanding the Function of Photoreceptor Cells**:
- Rod cells are responsible for vision in low light conditions (scotopic vision) and are more sensitive to light.
- Cone cells are responsible for color vision and function best in bright light (photopic vision).

4. **Locating the Fovea**:
- The fovea is a specific area on the retina that is responsible for sharp central vision.
- It is characterized by a high density of cone cells and the absence of rod cells.

5. **Analyzing the Options**:
- The question provides four options regarding the characteristics of the fovea:
- More rods than cones are found.
- Cones are absent.
- High density of cones occurs, with no rods present.
- Only rod cells are present.

6. **Determining the Correct Answer**:
- The correct statement about the fovea is that it has a high density of cone cells and no rod cells.
- Therefore, the answer is: "High density of cone cells occurs, with no rods present."