Professor Geragos has found that in industrialized nations, the transition to adult roles has become increasingly prolonged. This period of development is called

Emerging adulthood.

Explanation:

The Emerging Adulthood is a Developmental period or stage theorized by Jeffrey Jensen Arnett.

According to Jeffrey, the emerging adulthood is a period between adolescence and adulthood. He based his theory on the Erikson's theory of psychological development. He proposed that after the nations became industrialized, people desired to go to college which led to impede in marriage and parenthood stage.

The emerging adulthood causes prolongevity in adulthood roles of marriage and parenthood.

In the given scenario, Professor Geragos is referring to this emerging adulthood of development.