Energy is always required to force molecules to move from areas of high concentration to areas of low concentration?
true or false

the answer is "a.) well–developed vascular system."

explanation:

answer : haversian

[explanation: -(compact bone is organized as parallel columns, known as haversian systems, which run lengthwise down the axis of long bones. these columns are composed of lamellae, concentric rings of bone, surrounding a central channel, or haversian canal, that contains the nerves, blood vessels, and lymphatic system of the bone)]