Twelve-year-old Teetham spent the whole summer at camp. When he returned home, his parents were surprised that he was taller, more muscular, and that his voice had deepened. These physical changes are examples of which of the following?

a. secondary sex characteristics

b. puberty

c. primary sex characteristics

d. egocentrism

b. puberty

Explanation:

Boys tend to look a little chubby and gangly (long arms and legs compared to the trunk) just prior to and at the onset of puberty. They start to experience a growth spurt as they progress further into puberty, with the peak occurring during the later stages of sexual maturation. Body proportions change during this spurt, as there is rapid growth of the trunk, at the legs to some extent too. Boys continue to fill out with muscle mass long after girls do, so that by the late teens a boy's body composition is only 12 percent fat, less than half that of the average girl's.