What could be the form of referent if the subject is always in plural form?

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.

Anne frank was a very difficult person because she would never listen to her moms sometimes her dad even though he was her favorite and in times like that it would make it harder for there parents and other people in the annex to deal with her and since they were just stuck in there the couldn’t do anything but grounding her but even that didn’t work. hope that :