Of the following, which is mismatched with its partner ?

Options

A. Agnathans - Jawless fish
B. Gnathostomata-Jawed fish
C. Chondrichthyes-Bony fish
D. Osteichthyes - Bony fish

Explanation

To determine which of the following pairs is mismatched, we need to analyze each option carefully:

1. **Agnatha - Jawless fishes**:
- Agnatha refers to a class of vertebrates that do not have jaws. This classification is correct.

2. **Gnathostomata - Jawed fishes**:
- Gnathostomata includes all vertebrates that possess jaws. This classification is also correct.

3. **Chondrichthyes - Bony fishes**:
- Chondrichthyes refers to cartilaginous fishes, such as sharks and rays, which have a skeleton made of cartilage rather than bone. This classification is incorrect as it mismatches with bony fishes.

4. **Osteichthyes - Bony fishes**:
- Osteichthyes refers to the class of fishes that have a bony skeleton. This classification is correct.

From the analysis, we can conclude that the mismatched pair is:

**Chondrichthyes - Bony fishes** (this is incorrect; Chondrichthyes are cartilaginous fishes).

### Final Answer:
The mismatched pair is **Chondrichthyes - Bony fishes**.

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