Final answer:
During puberty, adolescents undergo both a growth spurt in height and weight, and develop primary and secondary sexual characteristics, due to hormonal changes directed by the brain and the gonads.
Step-by-step explanation:
During puberty, an adolescent will c. both a and b. This period involves significant physiological changes including the adolescent growth spurt (AGS), where there is rapid growth in height and weight, as well as changes in body composition and shape. In addition, puberty is characterized by the development of primary and secondary sexual characteristics. Primary sexual characteristics pertain to the reproductive organs, whereas secondary sexual characteristics are the physical signs of sexual maturation not directly involving the reproductive organs, such as the appearance of facial hair in boys or the development of breasts in girls. These changes are orchestrated by hormones, with the gonadotropin-releasing hormone (GnRH) from the hypothalamus prompting the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary gland, which in turn stimulate the gonads to produce sex hormones.