Which of the following cell membranes is the most fluid? A. Membrane A, because it is composed of saturated fatty acids that have one or more cis bonds that form stable aggregations B. Membrane A, because it is composed of saturated fatty acids that lack weak hydrogen bonds that continually break and reform to permit macromolecule movement C. Membrane B, because is it composed of unsaturated fatty acids that form weak covalent bonds at the site of their cis bonds, which permit easy movement D. Membrane B, because it is composed of unsaturated fatty acids that have one or more bends, which prevent tight packing