Which of the following would show pentaradial symmetry and have a calcareous endoskeleton made up of ossicles ?

Options

A. Mollusca
B. Annelida
C. Arthropoda
D. Echinodermata

Answer

To solve the question "Which of the following would show pentaradial symmetry and have a calcareous endoskeleton made up of ossicles?" we need to analyze the options provided: Mollusca, Annelida, Arthropoda, and Echinodermata.

### Step-by-Step Solution:

1. **Understanding Pentaradial Symmetry**:
- Pentaradial symmetry is a type of radial symmetry where the body parts are arranged around a central axis in five parts. This is characteristic of certain marine organisms.

2. **Identifying Calcareous Endoskeleton**:
- A calcareous endoskeleton is an internal skeleton made of calcium carbonate. This feature is important for the classification of certain groups of animals.

3. **Analyzing the Options**:
- **Mollusca**: This group includes animals like snails and clams, which exhibit bilateral symmetry, not pentaradial symmetry.
- **Annelida**: This group consists of segmented worms, which also show bilateral symmetry.
- **Arthropoda**: This group includes insects, arachnids, and crustaceans, which again exhibit bilateral symmetry.
- **Echinodermata**: This group includes sea stars, sea urchins, and sea cucumbers. They exhibit pentaradial symmetry and have an endoskeleton made up of calcareous ossicles.

4. **Conclusion**:
- Based on the characteristics discussed, the correct answer is **Echinodermata**. They are the only group listed that shows pentaradial symmetry and possesses a calcareous endoskeleton made of ossicles.

### Final Answer:
**Echinodermata**