This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Unknown
Intramembranous ossification is the source of ? 
Select and explain. 
A. Flat bone, B. Long bone, C. Cancellous bone, D. Bone of the epiphysis
A: Flat bone
Answer: A: Flat bone 
Explanation: Intramembranous ossification is the development of bone from mesenchymal condensation. Mesenchyme cells give rise to osteoblasts, which lay down bone matrix and eventually form bone spicules. When the osteoblasts become enclosed, they are called osteocytes. The frontal, parietal, squamous portion of the temporal, and parts of the occipital bone are derived from intramembranous ossification.
Long bones develop from a cartilage model, which is called endochondral ossification Growth in length occurs by division of cells in the epiphyseal plate. Cancellous bone is spongy, or trabecular bone, which can result after either intramembranous or endochondral ossification.