Carbon atoms are able to a. give off electrons to form negative carbon ions b. bond with other carbon atoms to form long chains c. gain four extra electrons to form positive carbon ions d. form five single covalent bonds with their valence electrons

B

Explanation:

Carbon atoms usually have a Lewis electron configuration of 2.4. To gain a stable electron configuration of 2.8, they usually form covalent bonds with other atoms such as another carbon and hydrogen. Carbon does not form ionic bonds because it would require much more energy for the atom to gain 4 electrons or lose the 4 electrons to achieve electron configuration. This is why carbon is a significant atom of life due to its versatility in how it bonds with other atoms including other carbon atoms. It can also form single double and triple bonds giving rise to many compounds, with the same elements, but with different properties.

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)]