Archinephros occurs in

Options

A. Adult Hagfish
B. Larva of Hegfish
C. Molluscs
D. Anamniotes

Answer

To solve the question "Archinephros occurs in," we will analyze the options provided and identify the correct answer step by step.

### Step-by-Step Solution:

1. **Understanding Archinephros**:
- Archinephros is referred to as the ancestral kidney and is an important structure in the evolutionary context of excretory systems.

2. **Analyzing the Options**:
- **A. Adult hagfish**: While hagfish are known to have a unique excretory system, adult hagfish do not retain the archinephros.
- **B. Larva of hagfish**: The larvae of hagfish do possess the archinephros, which is crucial for their excretory function.
- **C. Mollusk**: Mollusks have a different type of excretory system and do not have archinephros.
- **D. Anamniote**: Anamniotes include various groups of animals, but the term is too broad and does not specifically indicate the presence of archinephros.

3. **Identifying the Correct Answer**:
- Based on the analysis, the archinephros is retained specifically in the larvae of hagfish. Therefore, the correct answer is **B. larva of hagfish**.

### Final Answer:
Archinephros occurs in **B. larva of hagfish**.