Final answer:
The Civil Rights Movement had the most significant impact on social change in the 1960s, achieving crucial legislative victories and influencing other minority movements.
Step-by-step explanation:
The question asks which movement had the most significant impact on social change in the 1960s. The Civil Rights Movement is widely considered to have had the most profound effect on social change during that era. Spurred by grassroots activists and prominent events such as Martin Luther King's speech at the 1963 March on Washington, this movement achieved significant legislative victories, including the Civil Rights Act of 1964 and the Voting Rights Act of 1965, which were pivotal in challenging racial segregation and discrimination. While other movements such as the Feminist Movement, the Anti-War Movement, and the Environmental Movement also played crucial roles in driving social change, the Civil Rights Movement's direct impact on legislation and social policies, as well as its influence on other minority movements, marked it as a defining force of the decade.