Some characters are given below
i. Bilaterally symmetrical
ii. Triploblastic
iii. Segmented
iv. Coelomate
Which of the two phyla are characterized by the above all characters?

Options

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

Answer

To solve the question regarding which two phyla are characterized by the given traits (bilaterally symmetrical, triploblastic, segmented, and coelomate), we can follow these steps:

### Step 1: Understand the Characteristics
1. **Bilaterally Symmetrical**: Organisms can be divided into two identical halves along one plane.
2. **Triploblastic**: Organisms have three germ layers: ectoderm, mesoderm, and endoderm.
3. **Segmented**: The body is divided into segments, both externally and internally.
4. **Coelomate**: There is a body cavity (coelom) present between the body wall and gut, lined by mesoderm.

### Step 2: Analyze the Options
We need to evaluate the provided options based on the characteristics:

- **A. Annelida and Arthropoda**
- **B. Annelida and Mollusca**
- **C. Arthropoda and Mollusca**
- **D. Arthropoda and Echinodermata**

### Step 3: Evaluate Each Option
1. **Annelida and Arthropoda**:
- Both are bilaterally symmetrical, triploblastic, segmented, and coelomate.
- **Conclusion**: This option satisfies all four characteristics.

2. **Annelida and Mollusca**:
- Annelida is bilaterally symmetrical, triploblastic, segmented, and coelomate.
- Mollusca is bilaterally symmetrical and triploblastic but is generally unsegmented.
- **Conclusion**: This option does not satisfy all characteristics.

3. **Arthropoda and Mollusca**:
- Arthropoda is bilaterally symmetrical, triploblastic, segmented, and coelomate.
- Mollusca is bilaterally symmetrical and triploblastic but is unsegmented.
- **Conclusion**: This option does not satisfy all characteristics.

4. **Arthropoda and Echinodermata**:
- Arthropoda is bilaterally symmetrical, triploblastic, segmented, and coelomate.
- Echinodermata is characterized by radial symmetry in adults, although they may show bilateral symmetry in larvae.
- **Conclusion**: This option does not satisfy all characteristics.

### Step 4: Final Answer
After evaluating all options, the only option that satisfies all four characteristics (bilaterally symmetrical, triploblastic, segmented, and coelomate) is:
**A. Annelida and Arthropoda**