Which of the folllowing statements regarding the skeleton are correct ? Please select all that apply.
(a) The shaft of a long bone is called the diaphysis.
(b) The `"oraganic"` `"matrix"` of bone is secreted by chondroblasts.
(c) Dividing cartilage cells are situated in the marrow cavity of long bones
(d) Bone remodelling is a function of the activty marrow cavity of long bones
(e) The long bones develop from fibrous connective tissue
(f) Most bones are formed by endochondral ossification of a hyaline cartilage model
(g) The principal inorganic components of bones are calcium and phosphates.

Options

A. `abcd`
B. `adfg`
C. `bdfg`
D. `abdc`

Explanation

To solve the question regarding the correctness of statements about the skeleton, let's analyze each statement one by one:

### Step-by-step Solution:

1. **Statement (a)**: "The shaft of a long bone is called the diaphysis."
- **Analysis**: This statement is true. The diaphysis is indeed the long shaft of a long bone.
- **Conclusion**: Correct.

2. **Statement (b)**: "The organic matrix of bone is secreted by chondroblasts."
- **Analysis**: This statement is false. Chondroblasts are responsible for secreting cartilage, not bone. The organic matrix of bone is secreted by osteoblasts.
- **Conclusion**: Incorrect.

3. **Statement (c)**: "Dividing cartilage cells are situated in the marrow cavity of long bones."
- **Analysis**: This statement is also false. Dividing cartilage cells (chondrocytes) are located in the lacunae, not in the marrow cavity.
- **Conclusion**: Incorrect.

4. **Statement (d)**: "Bone remodeling is a function of the activity of the marrow cavity of long bones."
- **Analysis**: This statement is true. Bone remodeling involves the activity of cells in the marrow cavity, including osteoblasts and osteoclasts.
- **Conclusion**: Correct.

5. **Statement (e)**: "The long bones develop from fibrous connective tissue."
- **Analysis**: This statement is false. Long bones primarily develop from hyaline cartilage through a process called endochondral ossification.
- **Conclusion**: Incorrect.

6. **Statement (f)**: "Most bones are formed by endochondral ossification of a hyaline cartilage model."
- **Analysis**: This statement is true. Most bones in the body do indeed form from a hyaline cartilage model via endochondral ossification.
- **Conclusion**: Correct.

7. **Statement (g)**: "The principal inorganic components of bones are calcium and phosphates."
- **Analysis**: This statement is true. Calcium and phosphate are the main inorganic components that provide strength and structure to bones.
- **Conclusion**: Correct.

### Summary of Correct Statements:
- The correct statements are (a), (d), (f), and (g).

### Final Answer:
The correct options are **(a), (d), (f), and (g)**.