What element is undergoing reduction (if any) in the following reaction?
zn(s) + 2 agno3(aq) → zn(no3)2(aq) + 2 ag(s)
zn goes from 0 --> +2
ag from +3 --> 0 reduced
no3 from -1 --> -2 ?

The correct answer is Ag. 

Ag is the element that is undergoing reduction in the given reaction. Reduction refers to a gain of electrons and a decrease in oxidation number. So based in all the given reaction, Ag is the element that is undergoing reduction. I hope this answer helped you. 

C) electrons encircling a nucleus with neutrons and protons