Select the correct option.

Options

A. 8th, 9th ,and 10 pairs of ribs articulate directly with the sternum.
B. 11th and 12th pairs of ribs are connected to sternum by hyaline cartilage.
C. Each rib is a flat thin bone and all the ribs are connected dorsally to the thoracic vertebrae and ventrally to the sternum
D. There are seven pairs of vertebrosternal , three pairs of vertebrochondral and two pairs of vertebral ribs.

Answer

To solve the question, we need to evaluate the given statements about the ribs and identify the correct option. Let's go through the statements one by one.

### Step-by-Step Solution:

1. **Evaluate the First Statement:**
- The first statement claims that the 8th, 9th, and 10th pairs of ribs articulate directly with the sternum.
- **Analysis:** This statement is incorrect. The 8th, 9th, and 10th pairs of ribs do not connect directly to the sternum; instead, they connect to the 7th rib via hyaline cartilage.

2. **Evaluate the Second Statement:**
- The second statement states that the 11th and 12th pairs of ribs are connected to the sternum by hyaline cartilage.
- **Analysis:** This statement is also incorrect. The 11th and 12th pairs of ribs are known as floating ribs and do not connect to the sternum at all.

3. **Evaluate the Third Statement:**
- The third statement claims that each rib is a flat thin bone and all ribs are connected dorsally to the thoracic vertebrae and ventrally to the sternum.
- **Analysis:** This statement is incorrect. While ribs are indeed flat and thin bones, they connect dorsally to the thoracic vertebrae and ventrally to the sternum, but the phrasing is misleading.

4. **Evaluate the Fourth Statement:**
- The fourth statement says that there are 7 pairs of vertebrosternal ribs, 3 pairs of vertebrochondral ribs, and 2 pairs of vertebral ribs.
- **Analysis:** This statement is correct. There are indeed 7 pairs of vertebrosternal ribs (true ribs), 3 pairs of vertebrochondral ribs (false ribs), and 2 pairs of floating ribs (vertebral ribs).

### Conclusion:
The correct option is the fourth statement, which accurately describes the classification of ribs.