Which noun or pronoun does herself emphasize in the sentence below?

Mary herself brought the group project homework to our class and gave it to me.

A.
me
B.
Mary
C.
class
D.
our

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.