Choose the correct statement

Options

A. All reptiles have a three - chambered hear
B. All pisces have gills covered by an operculum
C. All mammals are viviparous
D. All cyclostomes do not possess jaws and paired fins.

Answer

To solve the question "Choose the correct statement," we will analyze each of the given options one by one.

### Step-by-Step Solution:

1. **Analyze Option A: "All reptiles have a three-chambered heart."**
- Most reptiles do have a three-chambered heart, but crocodiles are an exception as they possess a four-chambered heart.
- **Conclusion:** This statement is incorrect.

2. **Analyze Option B: "All fishes have gills covered by an operculum."**
- Only bony fishes (Osteichthyes) have gills covered by an operculum. Cartilaginous fishes (Chondrichthyes), like sharks and rays, do not have this feature.
- **Conclusion:** This statement is incorrect.

3. **Analyze Option C: "All mammals are viviparous."**
- While most mammals are viviparous (giving birth to live young), there are exceptions such as monotremes (e.g., echidna and platypus) that lay eggs.
- **Conclusion:** This statement is incorrect.

4. **Analyze Option D: "All cyclostomes do not possess jaws and paired fins."**
- Cyclostomes, which include lampreys and hagfish, are characterized by the absence of jaws and paired fins.
- **Conclusion:** This statement is correct.

### Final Answer:
The correct statement is **Option D: All cyclostomes do not possess jaws and paired fins.**

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