Albumin, one element of blood plasma, is an effective substitute for plasma in treating or preventing shock, the collapse of blood vessels due to a drop in the liquid volume of the bloodstream. Injected into the bloodstream, albumin absorbs enough liquid from surrounding tissues to keep the blood vessels open. It has an advantage over plasma because it can be made available for emergencies while taking up a fraction of the shipping and storage space of plasma. Of the following, which one best illustrates the principle illustrated by the stated advantage of using albumin as a substitute for plasma? ['A newspaper can increase advertising revenue without increasing its bulk or weight if it is printed in a smaller format.', 'Hardbound books can be a better choice than paperbacks despite their extra bulk if the books need to be more durable than paperbacks.', 'An advantage that compact discs have over vinyl records is that they are also used for storing information for computers, so advances in computer disc technology will probably apply to compact discs used for music.', 'Dehydrated foods have much the same food value as ordinary foods and are more convenient for hikers because they are lighter and take up less space in backpacks.']