One very special feature in the earthworm pheretima is that

Options

A. Fertilization of eggs occurs inside the body .
B. The typholosole greatly increases the effective absroption area of the digested food in the intestine.
C. The S-shaped sete embedded in the intergument are the defensive weapons used against the enemies.
D. It has a long dorsal tubular heart.

Answer

To answer the question about the special feature of the earthworm Pheretima, we will analyze each option provided and determine which one correctly describes a notable characteristic of this organism.

### Step-by-Step Solution:

1. **Evaluate Option 1: Fertilization of eggs occurs inside the body.**
- The fertilization of eggs in earthworms does not occur inside the body. Instead, the eggs are fertilized by sperm cells within a cocoon that is deposited in the soil. Therefore, this statement is incorrect.

2. **Evaluate Option 2: Typhosol greatly increases the effective absorption area of digested food in the intestine.**
- The typhosol is an internal median fold of the dorsal wall of the intestine in earthworms. It significantly increases the surface area for absorption of nutrients. This statement is correct and highlights a special feature of earthworms.

3. **Evaluate Option 3: S-shaped setae embedded in the integuments are defensive weapons.**
- The S-shaped setae are actually embedded in the epidermal pits and primarily serve the purpose of locomotion, not defense. Therefore, this statement is incorrect.

4. **Evaluate Option 4: It has a long dorsal tubular heart.**
- Earthworms have a segmented heart, not a long dorsal tubular heart. This statement is also incorrect.

5. **Conclusion:**
- After evaluating all the options, the correct answer is Option 2: "Typhosol greatly increases the effective absorption area of digested food in the intestine."

### Summary:
The special feature of the earthworm Pheretima is the presence of the typhosol, which enhances the absorption of digested food in the intestine.