Answer:
The strongest argument the author makes is that no child reaches maturity before the age of 20.
Step-by-step explanation:
The author states that children only reach biological maturity at the age of 20, for this reason, the author shows a series of supporting details that expose evidence of human immaturity up to the age of 20. For this reason, it is not recommended that young people under the age of 20 be treated as responsible adults and assume responsibilities that are too large for their mental and physical abilities.