What is a primary change occurring in both primary and secondary sexual characteristics during puberty?

The answer focuses on changes in reproductive organs because both primary and secondary sexual characteristics are directly related to the maturation of the reproductive system during puberty. This period is characterized by significant biological transformations that prepare the body for sexual reproduction.

Primary sexual characteristics specifically refer to the physical changes in the reproductive organs themselves, such as the development of the penis and testes in males or the maturation of the ovaries and uterus in females. Secondary sexual characteristics, which become more prominent during puberty, include features such as breast development and the appearance of body hair, which are influenced by the hormonal changes occurring as the reproductive system matures.

Other options represent changes that occur during puberty but do not encompass the direct changes in the reproductive organs. For instance, increases in muscle mass and height growth spurts are notable changes during this time primarily related to growth and development but are not specific to sexual maturation. Weight gain can also occur and may be associated with overall growth during puberty, yet it does not specifically relate to the primary and secondary sexual characteristics in the same direct manner as the development of reproductive organs. Thus, the emphasis on the changes in reproductive organs accurately reflects a fundamental aspect of sexual development during puberty.