2. Who tend to disagree with their parents about homework？
A. Teens with a larger amygdala
B. Teens with a larger frontal cortex.
C. Teens who are eager to discuss opinions
D. Teens who are positive about small events
3. What does the underlined word”this” in the last paragraph refer to？
A Brain change.
B Huge knowledge.
C Brain power.
D. Rare opportunity
4 What is the purpose of this text？
A. To compare two studies.
B. To honor some scientists
C. To recommend a learning approach
D To explain a biological phenomenon