Answer:
The correct answer is option a, that is, there is substantial gray matter growth.
Step-by-step explanation:
Till the age of six, the brains become 90 to 95 percent of the size of an adult's brain. However, the brain still requires many remodeling so that it can work as the brain of an adult. Some of the modifications in the brain take place prior to puberty, while some take place afterward. The modifications in the brain take place on the basis of age, hormonal changes and experience in puberty.
The gray matter increases at the time of early puberty is that since the time of birth the gray matter is weeded out spontaneously so that the individual can learn more effectively and can use the fundamental functions like walking and talking, along with other functions easily.