Which part of the spine will have fewer individual bones as you age?

• A. Cervical vertebrae
• B. Thoracic vertebrae
• C. Lumbar vertebrae
• D. Sacrum

Answer: (D)

Verified step by step guidance

1. Understand that the human spine is composed of several regions: cervical, thoracic, lumbar, sacrum, and coccyx.
2. Recognize that the sacrum is initially composed of five separate vertebrae in early life.
3. Learn that as a person ages, these five sacral vertebrae fuse together to form a single bone, the sacrum.
4. Compare this with other regions of the spine, such as cervical, thoracic, and lumbar, which do not undergo such fusion and remain as individual bones.
5. Conclude that the sacrum is the part of the spine that will have fewer individual bones as you age due to the fusion of its vertebrae.