Summarization：the paragraph is followed by an incomplete phrase or sentence which summarizes the main idea of the paragraph. Spell out the missing letter of the word on your answer sheet.

Probably the most primitive reason for teenage rebelliousness is physical in nature. At about the beginning of adolescence, children are undergoing profound hormonal changes as their bodies go through puberty. Their bodies are telling them that they are no longer children, and yet their parents are still treating them as children.
Reasons why teenagers r their parents.