Endoskeleton of bony vertebrates, jawless vertebrates is formed by  

Options

A. Hyaline cartilage
B. Bones
C. Bones & cartilage
D. Fibrous cartilage

Answer

To answer the question regarding the formation of the endoskeleton in bony vertebrates and jawless vertebrates, we can follow these steps:

### Step-by-Step Solution:

1. **Define Vertebrates**:
- Vertebrates are animals that belong to the subphylum Vertebrata, characterized by the presence of a vertebral column (backbone).

2. **Understand Endoskeleton**:
- The endoskeleton is the internal skeleton of an organism, as opposed to an exoskeleton, which is external.

3. **Identify Bony Vertebrates**:
- Bony vertebrates, as the name suggests, have an endoskeleton primarily made of bones. This group includes most fish, amphibians, reptiles, birds, and mammals.

4. **Identify Jawless Vertebrates**:
- Jawless vertebrates, such as lampreys and hagfish, belong to the superclass Agnatha. They are considered more primitive and have an endoskeleton made of cartilage rather than bone.

5. **Analyze the Options**:
- The options provided are:
- A) Hyaline cartilage
- B) Bones
- C) Bones and cartilage
- D) Fibrous cartilage
- From our understanding:
- **A)** Hyaline cartilage is incorrect as it is a type of cartilage found in specific areas but does not represent the endoskeleton of jawless vertebrates.
- **B)** Bones alone cannot be correct since jawless vertebrates do not have a bony endoskeleton.
- **C)** Bones and cartilage is the correct answer because bony vertebrates have bones, while jawless vertebrates have cartilage.
- **D)** Fibrous cartilage is also incorrect as it does not represent the composition of the endoskeleton in either group.

6. **Conclusion**:
- Therefore, the correct answer is **C) Bones and cartilage**, as it accurately describes the endoskeleton composition of both bony vertebrates and jawless vertebrates.