The resistance of a conductor is proportional to its length. suppose that the lengths of the two samples were doubled. how would this affect their electrical resistance at 20 k?

a.) the resistance of both material a and material b would increase.
b.) the resistance of both material a and material b would not change.
c.) the resistance of material b would increase, but the resistance of material a would not change.
d.) the resistance of material a would increase, but the resistance of material b would not change.