select the features which is not applicable to Annelida.

Options

A. Organ system level of organization
B. Closed type of circulatory system
C. Protenephridia for excretion
D. Tube within tube body plan

Answer

To solve the question of which feature is not applicable to Annelida, let's analyze each option step by step:

1. **Organ System Level of Organization**: Annelids possess a complex organ system level of organization. They have specialized organs for different functions, which is characteristic of more advanced organisms. This feature is applicable to Annelida.

2. **Closed Type of Circulatory System**: Annelids have a closed circulatory system, meaning that their blood is contained within vessels. This is another feature that is applicable to Annelida.

3. **Protonephridia for Excretion**: Protonephridia are excretory structures found in some invertebrates, particularly in flatworms (Platyhelminthes). Annelids, however, utilize nephridia for excretion, not protonephridia. Therefore, this feature is **not applicable** to Annelida.

4. **Tube Within Tube Body Plan**: Annelids exhibit a tube within a tube body plan, which means they have a separate mouth and anus. This feature is applicable to Annelida.

Based on the analysis, the feature that is **not applicable** to Annelida is **protonephridia for excretion**.

### Summary of the Solution:
- Organ System Level of Organization: Applicable
- Closed Type of Circulatory System: Applicable
- Protonephridia for Excretion: **Not Applicable**
- Tube Within Tube Body Plan: Applicable

Thus, the answer is **Protonephridia for Excretion**.