Which statement about Carbohydrates is true? Some have Protons and some do not.
Some are polymers and some are not.
They all have a positive charge.
They are all polymers.

i was thinking 4.0 v hope this

trachea, alveoli, lung capillaries, arteries

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)]