The correct answer is A. 12.
Ribs are long, curved bones that form part of the rib cage. They are attached to the spine at the back and to the sternum (breastbone) at the front. There are 12 pairs of ribs in humans, with the first 7 pairs being attached to the sternum by costal cartilage. The 8th, 9th, and 10th pairs are called floating ribs because they are not attached to the sternum. The 11th and 12th pairs are called false ribs because they are only attached to the 7th rib by costal cartilage.
The ribs protect the lungs, heart, and other organs in the chest. They also help with breathing by expanding and contracting the rib cage.
The following are the brief descriptions of each option:
- Option A: 12. This is the correct answer. There are 12 pairs of ribs in humans.
- Option B: 10. This is incorrect. There are 12 pairs of ribs in humans, not 10.
- Option C: 14. This is incorrect. There are 12 pairs of ribs in humans, not 14.
- Option D: 11. This is incorrect. There are 12 pairs of ribs in humans, not 11.