The lips undergo changes with aging, as do all parts of the body. Some changes may indicate a medical issue; others are harmless. As people age, the lips tend to become thinner. Deficiencies of certain vitamins and minerals can lead to inflammation of the lips (cheilitis), causing them to become red, cracked, painful, swollen, and/or scaly. Deficiency of which of the following vitamins or minerals can cause these symptoms?