During puberty, what hormone primarily drives the change from a girl to an adult?

The transformation from girlhood to adulthood during puberty is primarily driven by oestrogen. This hormone is crucial for the development of secondary sexual characteristics in females, which include the growth of breasts, the widening of hips, and the onset of menstruation. Oestrogen plays a significant role in regulating the menstrual cycle and promoting the development of the female reproductive system.

In contrast, while progesterone is involved in regulating the menstrual cycle and maintaining pregnancy, it does not play the primary role during the onset of puberty. Testosterone, although it influences various aspects of puberty in males, is not the primary hormone for the development of female secondary sexual characteristics. Follicle-stimulating hormone is important in reproductive health and function, but it does not drive the physical changes associated with the transition into adulthood. Therefore, among the options available, oestrogen is the hormone that primarily facilitates the changes seen during female puberty.