Choose the correct statement

Options

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

Answer

To solve the question "Choose the correct statement," we need to evaluate each of the provided statements one by one to determine which one is true.

### Step-by-Step Solution:

1. **Evaluate Statement 1**: "All mammals are baby parrots."
- This statement is **false**. Mammals are a distinct class of animals that includes various species, such as humans, dogs, and platypuses. The platypus is an example of an oviparous mammal, meaning it lays eggs, and is not related to parrots in any way.

**Hint**: Remember that mammals are a diverse group and not limited to any specific type of animal.

2. **Evaluate Statement 2**: "All cyclostomes do not possess the jaw and the paired fins."
- This statement is **true**. Cyclostomes, which include lampreys and hagfish, are jawless fish and do not have paired fins. This is a defining characteristic of this class.

**Hint**: Cyclostomes are known for their lack of jaws, which is a key feature that distinguishes them from other fish.

3. **Evaluate Statement 3**: "All reptiles have a three-chambered heart."
- This statement is **false**. While many reptiles do have a three-chambered heart, crocodiles are an exception as they possess a four-chambered heart. This makes the statement incorrect.

**Hint**: Look for exceptions in biological classifications, as they can change the validity of general statements.

4. **Evaluate Statement 4**: "All fishes have gills covered by an operculum."
- This statement is **false**. Fishes are divided into two classes: Osteichthyes (bony fishes) which do have an operculum covering their gills, and Chondrichthyes (cartilaginous fishes like sharks and rays) which do not have an operculum.

**Hint**: Understand the differences between bony and cartilaginous fishes to clarify the presence or absence of operculum.

### Conclusion:
After evaluating all the statements, the only correct statement is **Statement 2**: "All cyclostomes do not possess the jaw and the paired fins."