I believe the answer is A) Metals. This is because metal is naturally extremely conductive. So if the researcher wanted to find a super conductive wire, then you would most certainly look in metal.
You simply add the volumes :) If this was a case that involved titration, you would use the formula M1V1 = M2V2. I do not know if that is what you were referring to but based on the information you gave, you simply add the two volumes.
