Select the most formal statement. you should always floss before brushing. one should always floss before brushing. i should always floss before brushing. none of the above is formal.

You should always floss before brushing.
i think

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.