What is the best explanation why coiling takes place?

How is ribosomal rna useful as a molecular clock? a. a large portion of the dna ring is not vital to structure or function, allowing it to accumulate neutral mutations. b. its rate of mutation increases over time as organisms continue to evolve and differentiate from each other. c. a slow mutation rate makes it useful for determining evolutionary relationships between ancient species. d. it is only found in select organisms, making it easier to compare relationships between species that have it.

Several billion years ago which gas was the least prevailant in the atmosphere

What process decreases the salinity of ocean water? decreased precipitationdecreased melting of glaciersincreased evaporationincreased runoff from rivers