Excretory organs in chaetopterus are

Options

A. absent
B. protonephridia
C. renette glands
D. mentanephridia

Answer

### Step-by-Step Solution:

1. **Identify the Organism**: The question asks about the excretory organs in Chaetopterus. Chaetopterus is a genus of marine polychaete worms.

2. **Classify the Organism**: Chaetopterus belongs to the phylum Annelida and the class Polychaeta. Polychaetes are characterized by having numerous bristles or chaetae on their segments.

3. **Understand the Excretory System**: In Annelids, the excretory system is well-developed. The primary excretory organs in these organisms are called metanephridia.

4. **Confirm the Excretory Organ**: Metanephridia are found in each segment of the body and function to filter waste from the coelomic fluid, helping in excretion.

5. **Eliminate Incorrect Options**: The other options mentioned (such as protonephridia and renate glands) are not applicable to Chaetopterus as they belong to different phyla (Platyhelminthes and Aschelminthes, respectively).

6. **Conclude the Answer**: Therefore, the excretory organs in Chaetopterus are metanephridia.

### Final Answer:
The excretory organs in Chaetopterus are metanephridia.

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