The preoral segment in earthworms is called:

Options

A. prostomium
B. peristomium
C. clitellum
D. mouth

Answer

To solve the question "The preoral segment in earthworms is called:", we can follow these steps:

### Step 1: Understand the term "preoral"
- The term "preoral" refers to something that is located in front of or anterior to the mouth. This is crucial for identifying the correct segment in the earthworm.

### Step 2: Analyze the options provided
- The options given are:
1. Prostomium
2. Peristomium
3. Clitellum
4. Mouth

### Step 3: Evaluate each option
- **Option 1: Prostomium**
- The prostomium is indeed the head portion of the earthworm's body and is located anterior to the mouth. It serves as a sensory device. This fits the definition of a preoral segment.

- **Option 2: Peristomium**
- The peristomium is the first true segment of the earthworm's body, located just behind the prostomium and contains the mouth. Therefore, it cannot be the preoral segment.

- **Option 3: Clitellum**
- The clitellum is a thick, saddle-like ring found on the earthworm's body, important for reproduction, but it is not related to the mouth or preoral segment.

- **Option 4: Mouth**
- The mouth is the opening through which the earthworm takes in food, but it is not a preoral segment as it is located posterior to the prostomium.

### Step 4: Conclusion
- Based on the analysis, the correct answer to the question is **Prostomium**, as it is the preoral segment located in front of the mouth of the earthworm.

### Final Answer:
The preoral segment in earthworms is called **Prostomium**.

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