Shell is internal in

Options

A. Loligo
B. Chiton
C. Dentalium
D. Unio

Explanation

To answer the question "Shell is internal in," we will follow these steps:

### Step-by-Step Solution:

1. **Understanding the Shell**: The term "shell" typically refers to a hard protective outer layer found in various animals. It can be either internal or external depending on the species.

2. **Identifying the Phylum**: The question relates to the animal kingdom, specifically to organisms within the phylum Mollusca. Mollusks are known for having shells, which can be external or internal.

3. **Examples of Mollusks**: We need to identify specific examples of mollusks that have internal shells. Some common examples include:
- **Lolligo**: Also known as squid, which have an internal shell called the pen.
- **Chiton**: These have an external shell made up of eight overlapping plates.
- **Dantalius**: This refers to a type of tusk shell, which has a tubular external shell.
- **Union**: Refers to freshwater mussels, which have an external shell.

4. **Determining the Correct Answer**: Among the examples discussed, Lolligo (squid) is known for having an internal shell. The internal shell in squids is a remnant of the shell structure seen in their ancestors.

5. **Conclusion**: Based on the information gathered, we conclude that the correct answer to the question "Shell is internal in" is **Lolligo**.

### Final Answer:
**The shell is internal in Lolligo (squid).**

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