Long bones (humerus and femur) are made of compact bone and flat bones (frontal and occipital) are made of spongy bone. Spongy bone is only found in the body of the vertebra. All bones contain both compact and spongy bone. Compact bone is the primary bone type found in the body, spongy is limited to the skull bones.

The correct answer is: All bones contain both compact and spongy bone.

Step-by-step explanation:

Compact and spongy bone are two types of bone tissues.

Compact bone is denser and stronger, its main function is support and protection, and can be found under the periosteum and in the diaphyses of long bones. The structural unit of the compact bone is called an osteon and it arranges itself in concentric layers of calcified matrix.

Spongy bone, on the other hand, is much lighter and isn't arranged in concentric rings but has trabeculae (a network of matrix spikes that provides strength to the bone). Inside the spaces left by the trabeculae, there's red marrow (where hematopoiesis occurs).

All bones have a varying degree of the two types: compact bone generally forms the outer layer of the bone, while the spongy bone is in the inside of the bone.

answer: 15

step-by-step explanation: