Write a concise, well-organized essay of at least four paragraphs in response to the following prompt. Read the prompt carefully and be sure to address directly the issues it raises.

In 1970 the apartheid state seemed to be an invulnerable bastion of white minority rule on the African continent. Yet twenty years later it crumbled and fell. How do we explain this dramatic collapse? Your essay should begin with a brief survey of the history of internal and external opposition to apartheid from 1970 to 1990, and end with a discussion of the factors that best explain the ultimate demise of white supremacy in South Africa.