The nitrogenous bases form hydrogen bonds between opposing DNA strands to form the rungs of the "twisted ladder" or double helix of DNA or a biological catalyst that is found in the nucleotides. Adenine is always paired with thymine, and guanine is always paired with cytosine. These are known as base pairs.
Polymorphic. Polymorphisms
refer to spasmodic genetic variation within the same species of an organism resulting in varying forms of the species. Polymorphic viruses, mutate at faster rates hence the virus
population is subject to high rates of turnovers. The high divergence of various
species, such as influenza, is as a result of 0.01 mutations per nucleotide site
per year.
I believe that the answer is D. lichens growing on cooled lava. Hope it helps.