Compact bone is composed of tubular unites called?

The correct answer is osteons.

Osteons are the structural units of compact bone. Each osteon consists of a central Haversian canal surrounded by concentric layers of bone matrix, called lamellae. The Haversian canal contains blood vessels and nerves that supply the osteocytes, which are the bone cells that reside within the lamellae. Osteons are formed by the process of osteogenesis, which is the formation of new bone.