The frontal lobes become fully developed
at birth
at the beginning of adolescence
at the end of adolescence
by 25 years old

by 25 years old

Explanation:

A lot of people believe that at age 25 the adult phase really begins. This age does not have an arbitrary number, as only at age 25 our frontal lobes are fully developed. The frontal lobes are the most rational part of the brain, so this age brings more empathy and long-term perspective.

Because of the development of frontal lobes, 25-year-olds tend to have more rational attitudes, such as giving up addictions and seeking healthier, more realistic lifestyles.

answer; humanistic;

answer; allows decision to stand;