Adolescence became a defined life stage in the united states

a. sigmund freud developed his theories in the early 1900s.
b. jean piaget identified formal operational thinking as a separate stage.
c. president franklin roosevelt encouraged universal high school attendance.
d. the baby boom generation rebelled against the establishment.

The correct answer is letter C.

Explanation: Roosevelt was a very important president for the United States when he encouraged teenagers to go to school, this became something very serious and was a new way of seeing teenagers who were mostly working.

c. President Franklin Roosevelt encouraged universal high school attendance.

Explanation:

One of the factors that made adolescence a defined stage of life was the promotion of high school attendance. In the past, some people received secondary education and even higher education to become professionals. However, this was not universal. Between 1910 and 1940, changes were introduced to the American education system. This made high schools more common, easier to graduate from, and free. The changes led to a rise in school attendance. Adolescence in the United States was thereafter defined by the virtually universal experience of high school.

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Explanation: