Answer:
A. the rise of youth culture in the 1950s.
Step-by-step explanation:
One of the most important factors in the emergence of New Left organizations in the 1960s was the rise of youth culture in the 1950s. Before the 1950s, the transition from childhood to adulthood was very clear and swift, and there was little culture dedicated to those in between. This changed in the 1950s, when music, fashion and entertainment began to focus on the young. This celebration of youth was carried over to the 1960s, resulting in the development of a counterculture and the emergence of New Left organizations.