Please determine if this is internal or external and please write an explanation. :)

Why it's time to lay the stereotype of the 'teen brain’ to rest 1. part a: which statement identifies the central idea of the text? a experts have spent time researching how different the teenage brain is from adults’ brains, when they are actually more similar than different. b teenagers often engage in risky behavior to fulfill the narrative they have been told about how teenagers are supposed to behave. c explanations for why teenagers engage in risky behavior have been overly focused on brain development, rather than their natural need to explore the world. d teenagers’ risky behavior is influenced by the combined effects of their hormone levels and their brain development.