Originally developed for detecting air pollutants, a technique called proton-induced X-ray emission, which can quickly analyze the chemical elements in almost any substance without destroying it, is finding uses in medicine, archaeology and criminology.
proton-induced X-ray emission
OG says underline part is correct and hence A is answer...Can some one please explain the use of which here? Doesn't which refer here to emission and that is, in my opinion' wrong!
is a single Compount noun so which refers to proton-induced X-ray emission