Spongy or cancellous bones are

Options

A. Skull bones
B. Scapula
C. Femur
D. Ribs

Answer

### Step-by-Step Solution:

1. **Understanding Spongy or Cancellous Bones**:
- Spongy bones, also known as cancellous bones, are a type of bone that has a porous structure. They are lighter and less dense than compact bones.

2. **Identifying Examples of Spongy Bones**:
- The question provides four options: skull bones, scapula, femur, and ribs. We need to identify which of these is primarily composed of spongy bone.

3. **Analyzing Each Option**:
- **Skull Bones**: The skull has both compact and spongy bone, but it is not primarily classified as spongy bone.
- **Scapula**: The scapula (shoulder blade) is primarily made up of spongy bone between two layers of compact bone.
- **Femur**: The femur (thigh bone) is mainly a long bone with a central medullary cavity and is primarily composed of compact bone.
- **Ribs**: Ribs have a combination of both compact and spongy bone, but they are not classified as spongy bones.

4. **Conclusion**:
- Among the given options, the scapula is the best example of a bone that is primarily composed of spongy or cancellous bone.

5. **Final Answer**:
- The correct answer is **scapula**.