If a small droplet of triacylglycerol molecules is suspended in water, the fat molecules form a "ball of spaghetti" with no particular orientation. But if a droplet of phospholipid molecules is put in water, all the molecules point outward, toward the water. Phospholipids are forced into this orientation because phospholipids have __________.

• A. three fatty acid molecules, all pointing in different directions
• B. two fatty acid molecules pointing in different directions
• C. both a saturated fatty acid and an unsaturated fatty acid
• D. two charged or polar ends
• E. a charged or polar end and an uncharged or nonpolar end