Final answer:
The tissue that grows rapidly and then involutes during puberty to reach adult size is the breast tissue.
Step-by-step explanation:
The tissue that grows rapidly reaching 2x the adult size by age 10 and then involutes during the pubertal growth spurt to reach adult size is the breast tissue. As a female reaches puberty, breast development is one of the first visible changes. The breast tissue grows rapidly during this time, and then involutes to reach its adult size.