What is the best reference source to use to find the meaning of the word flume as it is used in this sentence from the passage?
a) almanac
b) thesaurus
c) dictionary
d) literature text

Okay, biology isn't exactly my strongest subject (it never has been), but i'm pretty sure the answer is nucleotides. dna is made up of nucleotides. each nucleotide contains a phosphate group, a sugar group, and a nitrogen base. there are four different nitrogen bases: adenine (a), thymine (t), guanine (g), and cytosine (c). a always pairs with t, and g always pairs with c.