Final answer:
Option B. The marked weight gains that occur during puberty correspond to increased muscle and bone growth in boys and increased body fat in girls. This is part of the sexual dimorphism in body composition and shape that develops during adolescence.
Step-by-step explanation:
The correct statement about sexual maturation and weight changes that occur during puberty is: D) Marked weight gains coincide with the onset of puberty. As adolescents enter puberty, they experience a rapid period of growth often referred to as a "growth spurt."
In girls, puberty begins with the development of breast tissue and is followed by growth of axillary and pubic hair. The growth spurt usually starts around age 9 to 11. In contrast, in boys, the initial sign of puberty is typically the enlargement of the testes, followed by pubic hair growth and other physical changes such as the deepening of the voice and facial hair development which occur later in the puberty sequence.
During adolescence, changes in the amount of body fat and muscle distribution lead to marked weight gains. Girls develop more body fat, particularly in the breasts and hips, contributing to the sexual dimorphism in adult body composition. Boys experience significant muscle and bone growth, particularly in the upper body, which contributes to their overall weight gain.