The pigmentation of which structures may increase during puberty?

During puberty, the pigmentation of the nipples and areola is likely to increase due to hormonal changes that occur in the body. These changes are primarily driven by sex hormones such as estrogen and testosterone, which influence various secondary sexual characteristics. In females, for instance, the areola may darken as part of the development of breasts and the preparation for lactation, while in males, there can also be changes in pigmentation as body composition and distribution of fat change.

The other structures listed do not experience the same level of change in pigmentation during puberty. Skin changes on the face can occur due to acne and oil production but do not typically involve significant pigmentation increases. Hair follicles may become more active, leading to hair growth, but they do not directly correlate with increased pigmentation in the same way the areola does. The pigmentation of eyes is influenced more by genetic factors than hormonal changes during puberty.