Excretory organs in Chaetopterus are

Options

A. 1)absent
B. 2)protonephridia
C. 3)renette glands
D. 4)metanephridia

Answer

### Step-by-Step Solution:

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

2. **Classify the Organism**: Chaetopterus belongs to the phylum Annelida and the class Polychaeta. Understanding the classification helps in identifying the characteristics of the organism.

3. **Understand Excretory Structures**: In annelids, the excretory system is crucial for waste elimination. The common types of excretory organs in different phyla include:
- Proton nephridia: Found in Platyhelminthes (flatworms).
- Metanephridia: Found in Annelida (including Chaetopterus) and Arthropoda.
- Rennet glands: Found in Nematoda (roundworms).

4. **Determine the Correct Excretory Organ**: For Chaetopterus, the excretory organ is metanephridia. This is a key feature of many annelids, including polychaetes.

5. **Evaluate the Options**: The options provided are:
- a) Absent
- b) Proton nephridia
- c) Rennet gland
- d) Metanephridia
After evaluating, the correct answer is option d) Metanephridia.

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

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