The common larva of polychaeta/annelida is

Options

A. Trochophore
B. Actinotrocha
C. Glochidium
D. Tornaria

Answer

To answer the question regarding the common larva of polychaeta/annelida, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for the common larval form found in polychaetes, which are a class within the phylum Annelida.

2. **Identify Polychaetes**: Polychaetes are a group of annelids characterized by having many bristles or setae. An example of a polychaete is Nereis.

3. **Review the Options**:
- **Trochophore**: This is a free-swimming larval stage that is indeed associated with polychaetes.
- **Actinotrocha**: This larval form is associated with phoronids, which belong to a different phylum.
- **Glochidium**: This larval stage is found in some mollusks, not polychaetes.
- **Tornaria**: This is the larval form of hemichordates, which are also not related to polychaetes.

4. **Analyze Each Option**:
- The **trochophore** is confirmed as the larval form of polychaetes.
- The other options (actinotrocha, glochidium, and tornaria) are associated with different phyla and therefore are incorrect.

5. **Conclusion**: Based on the analysis, the common larva of polychaeta/annelida is the **trochophore**.

### Final Answer:
The common larva of polychaeta/annelida is the **trochophore**.

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