Sea fur belongs to phylum A. Members of such phylum have:

Options

A. Bilateral symmetry
B. Blind sac body plan
C. Metamerism
D. Triploblastic nature

Answer

To solve the question regarding the characteristics of members of the phylum to which sea fur belongs, we can follow these steps:

### Step 1: Identify the Phylum
- Sea fur is commonly known as a member of the phylum Cnidaria. This phylum includes organisms like jellyfish, corals, and sea anemones.

### Step 2: Understand the Characteristics of Cnidarians
- Members of the phylum Cnidaria exhibit specific characteristics. We need to analyze the options provided in the question to determine which one accurately describes Cnidarians.

### Step 3: Evaluate the Options
1. **Bilateral Symmetry**:
- This is incorrect for Cnidarians. They exhibit radial symmetry, not bilateral symmetry.

2. **Blind Sac Body Plan**:
- This is correct. Cnidarians have a blind sac body plan, meaning they have a single opening that serves both as the mouth and the anus.

3. **Metamerism**:
- This is incorrect. Metamerism is a characteristic of phylum Annelida (segmented worms), not Cnidaria.

4. **Triploblastic Nature**:
- This is incorrect. Cnidarians are diploblastic, meaning they have two germ layers (ectoderm and endoderm), rather than three.

### Step 4: Conclusion
- Based on the evaluation of the options, the correct answer is that members of the phylum Cnidaria have a **blind sac body plan**.

### Final Answer
- The correct option is **B. Blind sac body plan**.

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