Which of the following is not a requisite of any respiratory surface to become highly efficient are:

Options

A. Large surface area
B. Thick walls
C. Rich blood supply
D. Fine and delicate surface area

Explanation

To determine which of the following is not a requisite for a respiratory surface to be highly efficient, we need to analyze each option provided:

1. **Large Surface Area**: A large surface area is essential for efficient gas exchange because it allows more area for oxygen and carbon dioxide to diffuse in and out of the organism.

2. **Thick Walls**: Thick walls would hinder the process of diffusion. For gas exchange to occur efficiently, the walls of the respiratory surface need to be thin to allow gases to pass through easily. Therefore, thick walls are not a requisite for an efficient respiratory surface.

3. **Rich Blood Supply**: A rich blood supply is crucial as it helps transport gases quickly to and from the respiratory surface, facilitating efficient gas exchange.

4. **Fine and Delicate Surface Area**: A fine and delicate surface area is important as it allows for better aspiration and gas exchange. A rough surface would impede this process.

Based on this analysis, the option that is not a requisite for an efficient respiratory surface is **Thick Walls**.

### Step-by-Step Solution:
1. **Identify the Options**: Read through the options provided.
2. **Analyze Each Option**: Consider the importance of each characteristic for a respiratory surface.
3. **Determine the Incorrect Option**: Identify which option does not contribute to efficient gas exchange.
4. **Conclude**: State that thick walls are not a requisite for an efficient respiratory surface.