How do red blood cells help animals?

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.

Eutrophication caused by human nutrient pollution.

In the sentence "a mining company will consider the distribution of coal when deciding how to mine the coal," what does the word distribution mean?