The model below represents a dna molecule.

the presence of which element best provides evidence that nucleotides are the building material used to make dna?

carbon
oxygen
nitrogen
phosphorus

Nitrogen

Explanation:

The nitrogenous bases of the two separate polynucleotide strands are bound together, according to base pairing rules (A with T and C with G), with hydrogen bonds to make double-stranded DNA.

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.