Final answer:
Intramembranous ossification is a process in which bone develops directly from sheets of undifferentiated connective tissue, and it is responsible for the formation of flat bones.
Step-by-step explanation:
Intramembranous ossification is a process of bone development from fibrous membranes. Compact and spongy bone develop directly from sheets of undifferentiated connective tissue. This process is involved in the formation of flat bones, such as the bones of the face, most cranial bones, and clavicles (collarbones).