Hard exoskeletom cephalothrax and gills for respiration are characteristics of

Options

A. Insecta
B. Myriapoda
C. Polychaeta
D. Crustacea.

Answer

To solve the question regarding the characteristics of hard exoskeleton, cephalothorax, and gills for respiration, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Characteristics**: The question mentions three specific characteristics:
- Hard exoskeleton
- Cephalothorax
- Gills for respiration

2. **Understand the Options**: The options provided are:
- A) Insecta
- B) Meriopoda
- C) Polychaeta
- D) Crustaceans

3. **Analyze Each Option**:
- **Insecta**: Insects have an exoskeleton, but they do not have a cephalothorax; they have a distinct head, thorax, and abdomen. They also breathe through tracheae, not gills.
- **Meriopoda**: This term is not commonly used in modern classifications; it may refer to myriapods (like centipedes and millipedes), which do not have a cephalothorax or gills.
- **Polychaeta**: This class of annelids (segmented worms) has a different body structure and does not possess a hard exoskeleton or cephalothorax.
- **Crustaceans**: Crustaceans, which include crabs, lobsters, and shrimp, have a hard exoskeleton, the head and thorax are fused to form a cephalothorax, and they respire using gills.

4. **Conclusion**: Based on the analysis, the only group that possesses all three characteristics (hard exoskeleton, cephalothorax, and gills for respiration) is **Crustaceans**.

5. **Final Answer**: Therefore, the correct answer is **D) Crustaceans**.