The cartilaginous fish include all except:

Options

A. lampreys
B. sharks
C. skates
D. rays

Explanation

To solve the question "The cartilaginous fish include all except:", we need to identify which of the given options does not belong to the category of cartilaginous fish.

### Step-by-Step Solution:

1. **Understand the Definition of Cartilaginous Fish**:
- Cartilaginous fish are those whose skeletons are made of cartilage instead of bone. This group is scientifically classified under the class Chondrichthyes.

2. **Identify the Options**:
- The options provided are:
- A) Lampreys
- B) Sharks
- C) Skates
- D) Rays

3. **Classify Each Option**:
- **Lampreys**: These belong to the genus Petromyzon and are part of the superclass Agnatha, which consists of jawless fish. They do not have a cartilaginous skeleton.
- **Sharks**: These are part of the class Chondrichthyes and have a cartilaginous skeleton.
- **Skates**: These also belong to the class Chondrichthyes and have a cartilaginous skeleton.
- **Rays**: Like sharks and skates, rays are also classified under Chondrichthyes and possess a cartilaginous skeleton.

4. **Determine the Answer**:
- Among the options, lampreys are the only ones that do not belong to the class Chondrichthyes. Instead, they belong to Agnatha, which means they are not cartilaginous fish.

5. **Conclusion**:
- Therefore, the answer to the question is **Lampreys**.

### Final Answer:
**Lampreys**

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