Nerve ring of earthworm is formed surrounding

Options

A. Pharynx
B. Gizzard
C. Stomach
D. None

Answer

To answer the question about the nerve ring of the earthworm, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure**: The nerve ring in earthworms is a part of their nervous system. It is formed by the fusion of ganglia (clusters of nerve cells) that encircle the esophagus.

2. **Identify the Location**: The nerve ring is located in the lower region of the earthworm, specifically around the fourth segment.

3. **Recognize the Components**: The nerve ring consists of the perineural ganglia, which are ventrally located. These ganglia are connected to subperineural ganglia.

4. **Determine the Surrounding Structure**: The nerve ring surrounds the esophagus of the earthworm. The esophagus is the tube through which food passes from the mouth to the stomach.

5. **Select the Correct Option**: Given the options:
- a) Perinix
- b) Gizzard
- c) Stomach
- d) None

The correct answer is that the nerve ring surrounds the esophagus, which is not explicitly listed in the options. However, since the question is about what the nerve ring surrounds, the closest option would be "none" as it does not directly surround any of the listed structures.

### Final Answer:
The nerve ring of the earthworm is formed surrounding the esophagus. Therefore, the correct answer is **d) None**.