Red bone marrow occurs in membranous
bones such as

Options

A. all flat bones of skull , vertebrae, sternum and ribs
B. only in centrum of vertebrae
C. only in centrum of vertebrae and skull
D. none of these

Answer

To answer the question regarding where red bone marrow occurs in membranous bones, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Function of Red Bone Marrow**:
Red bone marrow is responsible for the production of blood cells, including red blood cells, white blood cells, and platelets.

**Hint**: Remember that red bone marrow is crucial for hematopoiesis (blood cell formation).

2. **Identify Types of Bones**:
There are different types of bones in the human body, including flat bones, long bones, short bones, and irregular bones. Red bone marrow is primarily found in flat bones.

**Hint**: Flat bones are typically involved in protecting vital organs and providing a surface for muscle attachment.

3. **List Examples of Flat Bones**:
Flat bones include the skull, sternum, ribs, and the hip bones (pelvic girdle). These bones have a large surface area and are where red bone marrow is commonly found.

**Hint**: Think of the bones that form the protective casing around organs or are broad and flat.

4. **Consider the Options Given**:
The options provided are:
- A) All flat bones of a skull, vertebrae, and sternum and ribs
- B) Only in the centrum of the vertebrae
- C) Only in the centrum of vertebrae and the skull
- D) None of these

**Hint**: Look for the option that encompasses all the mentioned flat bones.

5. **Evaluate Each Option**:
- Option A includes all flat bones (skull, vertebrae, sternum, ribs), which is correct.
- Option B and C are too limited as they do not include all flat bones.
- Option D is incorrect as there are valid options.

**Hint**: The correct answer should include a comprehensive list of where red bone marrow is found.

6. **Select the Correct Answer**:
Based on the above evaluation, the correct answer is option A: "All flat bones of a skull, vertebrae, sternum, and ribs."

**Hint**: Always choose the most inclusive answer when multiple options are provided.

### Final Answer:
Red bone marrow occurs in membranous bones such as **all flat bones of the skull, vertebrae, sternum, and ribs**.