Which movement pressed for increased rights and an end to separate development, gaining young supporters until it was banned in 1977?

The Black Consciousness Movement is the correct answer as it played a pivotal role in advocating for increased rights and the end of apartheid's policy of separate development. Founded in the late 1960s, this movement emphasized the importance of psychological liberation and empowerment among Black South Africans, promoting pride in Black identity and culture. It attracted a significant number of young supporters, particularly students, who resonated with its message of self-worth and resistance against oppression.

The movement's influence grew throughout the early 1970s, particularly through the efforts of leaders like Steve Biko, who became a prominent figure in promoting the ideals of Black rule and self-affirmation. However, it faced severe repression, culminating in its banning in 1977. This suppression was a response to its rising popularity and its challenge to the apartheid state, highlighting the movement's impact on the political landscape of South Africa during this period.

Other movements mentioned also had a role in the struggle against apartheid, but they did not encapsulate the specific focus on psychological empowerment and the mobilization of young people to the same extent as the Black Consciousness Movement did.