In the following sentence, what is the antecedent of the pronoun "it"? the class members chose chicago to visit because it provides the best opportunity for education and entertainment.

Chicago is the antecedent of "it".

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.

So what's needed to be done?