Instead of calling the highway patrol or the sheriff, the car sped away from the accident.
adjective or adverb used incorrectly
misplaced or dangling modifier
unclear pronoun reference
illogical or incomplete comparison

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.