Answer is number 1
Oxygen O2
Ozone O3
Part of an organism, a nucleotide is a part
People who have darker skin have more melanin which is a black or dark brown pigment in the skin. When we are out in the sun our skin produces more melanin, which helps our skin be more resistant in the sun. This is why we tan.
Bacteria was the first life form :)
To support the axial load on the column as it is delivered by body mass and gravity
