The avian/reptilian eyes are peculiar because of the presence of

Options

A. Pecten
B. Large number of cones
C. Large pupil
D. Sensitive retina

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the peculiar features of avian (bird) and reptilian eyes. We need to identify what makes these eyes unique compared to other animals.

2. **Analyzing the Options**:
- **Option A: Pectin**: Pectin is a comb-like structure of blood vessels found in the choroid layer of the eyes of reptiles and birds. It plays a crucial role in nourishing the retina and contributes to the unique appearance of these eyes.
- **Option B: Large Number of Cones**: The number of cones in avian and reptilian eyes is similar to that in mammalian eyes. Therefore, this does not provide a unique characteristic.
- **Option C: Large Pupil**: While birds have large pupils that allow more light to enter and enhance color perception, this feature does not contribute to the peculiar appearance of their eyes.
- **Option D: Sensitive Retina**: Both birds and reptiles have sensitive retinas, but this characteristic does not alter the physical appearance of their eyes.

3. **Conclusion**: After analyzing all the options, the unique feature that makes avian and reptilian eyes peculiar is the presence of **pectin**.

### Final Answer:
The avian/reptilian eyes are peculiar because of the presence of **pectin**.

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