The correct answer is A. 12.
A typical human ribcage consists of 12 pairs of ribs, which are connected to the spine at the back and to the sternum (breastbone) at the front. The first seven pairs of ribs are called true ribs, and they are attached to the sternum directly. The next five pairs of ribs are called false ribs, and they are attached to the sternum indirectly through the cartilage of the seventh pair of ribs. The last two pairs of ribs are called floating ribs, and they are not attached to the sternum at all.
The ribs protect the lungs, heart, and other organs in the chest. They also help with breathing by expanding and contracting the chest cavity.
Here is a brief explanation of each option:
- Option A: 12. This is the correct answer. A typical human ribcage consists of 12 pairs of ribs.
- Option B: 14. This is incorrect. There are 12 pairs of ribs, not 14.
- Option C: 16. This is incorrect. There are 12 pairs of ribs, not 16.
- Option D: 24. This is incorrect. There are 12 pairs of ribs, not 24.