Prostomium is

Options

A. first anterior most segment
B. outgrowth from the peristomium
C. the second anterior most segment
D. third anterior most segment.

Answer

**Step-by-Step Solution:**

1. **Understanding the Term 'Prostomium':**
- Prostomium is defined as an outgrowth or projection from another part of the organism, specifically from the peristomium.

2. **Identifying the Peristomium:**
- The peristomium is the first segment of the earthworm, located at the anterior (front) end. It is the segment where the mouth opening is situated.

3. **Location and Function of Prostomium:**
- The prostomium is located above the peristomium and serves to cover the mouth when it is closed. It is a small fleshy lobe that plays a role in the earthworm's burrowing activities.

4. **Characteristics of Prostomium:**
- The prostomium is described as a muscular lobe. Its muscular nature aids in the burrowing process, which is essential for the earthworm's movement through soil.

5. **Analyzing the Options:**
- The question likely provides multiple-choice options regarding the definition of prostomium.
- The first option incorrectly states that prostomium is the first anterior most segment (this is actually the peristomium).
- The second option correctly identifies prostomium as an outgrowth from the peristomium.
- The third option incorrectly states that prostomium is the second anterior most segment.
- The fourth option is also incorrect.

6. **Conclusion:**
- The correct answer to the question "Prostomium is" is that it is an outgrowth from the peristomium.