The largest taxon is the Domain and the smallest is the species.
I believe the answer is c
Like DNA, RNA is made up of nucleotides. There are two differences that distinguish DNA from RNA: (a) RNA contains the sugar ribose, while DNA contains the slightly different sugar deoxyribose (a type of ribose that lacks one oxygen atom), and (b) RNA has the nucleobase uracil while DNA contains thymine.
If an enviornment uses way too much of a resorce and it starts to rapidly decrease it will start to become an nonrenuabla resorce (this is just an idea)