Final answer:
Brain and cranial bone growth are not 90%-95% complete by age 5. The brain mostly reaches 90% of its adult size by age 6, but the development of the frontal lobes continues into the early 20s.
Step-by-step explanation:
The statement that brain and cranial bone growth are about 90%-95% complete by age 5 is FALSE. According to the information provided, the brain does not increase in size very much during adolescence, with most of the increase in brain size occurring early in childhood. By the age of six, the brain has already attained about 90 percent of its adult size. However, the development of the frontal lobes, which are associated with planning, reasoning, memory, and impulse control, is important during this stage and continues into the early 20s.