Final answer:
Sarah-Jayne Blakemore proposed in 2003 that adolescents struggle with emotion control due to the ongoing development of their prefrontal cortex.
Step-by-step explanation:
In 2003, Sarah-Jayne Blakemore suggested that adolescents have difficulty controlling their emotions because their prefrontal cortex has not yet fully developed. This understanding aligns with the idea that the frontal lobes, responsible for judgment, impulse control, and planning, are still maturing into early adulthood. It's important to note that, according to Erikson's theory of psychosocial development, the main task of the adolescent is developing a sense of identity, which can be a challenging process when psychological and brain developments are still ongoing.