Identify the correct pair:

Options

A. Radially symmetrical - Coelenterates
B. Asymmetrical - Echinodermates
C. Bilaterally symmetrical - sponges
D. Biradially symmetrical - Platyhelminthes.

Answer

To solve the question of identifying the correct pair from the given options, we will analyze each option based on the symmetry characteristics of the organisms mentioned.

### Step-by-Step Solution:

1. **Understanding the Options:**
- Option A: Radially Symmetrical Silantrates
- Option B: Asymmetrical Echinodermates
- Option C: Bilaterally Symmetrical Sponges
- Option D: Biradially Symmetrical Platyhelminthes

2. **Analyzing Option A: Radially Symmetrical Silantrates**
- Silantrates (or Cnidarians) such as jellyfish and corals exhibit radial symmetry. This means their body can be divided into similar halves by multiple planes passing through the central axis.
- **Conclusion:** This option is correct.

3. **Analyzing Option B: Asymmetrical Echinodermates**
- Echinodermates (like starfish and sea urchins) typically exhibit bilateral symmetry in their larval stages and pentamerous radial symmetry as adults, but they are not asymmetrical.
- **Conclusion:** This option is incorrect.

4. **Analyzing Option C: Bilaterally Symmetrical Sponges**
- Sponges are known for their asymmetrical body structure. They do not have a defined symmetry.
- **Conclusion:** This option is incorrect.

5. **Analyzing Option D: Biradially Symmetrical Platyhelminthes**
- Platyhelminthes (flatworms) are bilaterally symmetrical, meaning they can be divided into two mirror-image halves along a single plane.
- **Conclusion:** This option is incorrect.

6. **Final Conclusion:**
- The only correct pair from the options provided is **Option A: Radially Symmetrical Silantrates**.

### Summary of the Correct Answer:
The correct pair is **Option A: Radially Symmetrical Silantrates**.

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