To which classes do the following animals belong? A-Petromyzon, B-Scoliodon, C-Pristis

Options

A. a) A-Cyclostomate, B-Chondrichthyes, C-Chondrichthyes
B. b) A-Osteichthyes, B-Chondrichthyes, C-Chondrichthyes
C. c) A-Oseichthyes, B-Chondrichthyes, C-Osteichthyes
D. d) A-Osteichthyes, B-Chondrichthyes, C-Cyclostomata

Explanation

To determine the classes to which the animals Petromyzon, Scoliodon, and Pristis belong, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Phylum**:
- All three animals (Petromyzon, Scoliodon, and Pristis) belong to the phylum **Chordata**. This phylum includes animals that have a notochord at some stage of their life cycle.

2. **Identify the Subphylum**:
- Within the phylum Chordata, these animals fall under the subphylum **Vertebrata**, which includes animals with a backbone.

3. **Classify into Divisions**:
- The subphylum Vertebrata can be divided into two main groups:
- **Agnatha**: Jawless fish.
- **Gnathostomata**: Jawed vertebrates.

4. **Classify Petromyzon**:
- Petromyzon is a jawless fish, which means it belongs to the class **Cyclostomata**. This class includes all jawless fish.

5. **Classify Scoliodon**:
- Scoliodon is a type of shark, which has a jaw. Therefore, it belongs to the class **Chondrichthyes**. This class includes cartilaginous fish such as sharks and rays.

6. **Classify Pristis**:
- Pristis, commonly known as the sawfish, is also a cartilaginous fish. Thus, it too belongs to the class **Chondrichthyes**.

7. **Summarize the Classes**:
- Therefore, we summarize the classes as follows:
- A. Petromyzon: **Cyclostomata**
- B. Scoliodon: **Chondrichthyes**
- C. Pristis: **Chondrichthyes**

### Final Answer:
- A. Petromyzon - Cyclostomata
- B. Scoliodon - Chondrichthyes
- C. Pristis - Chondrichthyes