Final answer:
Estrogens are the hormones responsible for the changes Sally is experiencing, such as breast enlargement and the development of a more womanly body shape during puberty.
Step-by-step explanation:
The hormone directly responsible for Sally's breasts enlarging and her body beginning to look more womanly is estrogens. During puberty, estrogens produced by the ovaries cause the development of female secondary sexual characteristics. These changes include the increased development of breast tissue, redistribution of body fat to the hips, legs, and breasts, and the maturation of the uterus and vagina. Estrogens, along with testosterone, are responsible for the adolescent growth spurt and play a crucial role in the maturation of the female reproductive system.