The correct answer is C, historical context. There have been many literary movements throughout time, starting from the old era, to the postmodernism that is today. And usually, each literary movement was created as a reaction to the previous movement - romanticism was before realism, modernism was after realism, etc. The historical context demanded changes, and as years passed, people and their needs changed, and thus new literary movements were created. During Queen Victoria, there was Victorian era, where everyone was reserved and cared about their reputation, and that reflected in the literature. When people needed something modern, modernism emerged. When technology thrived, cyber punk literature was created. Every era demands a different approach to literature, and thus new movements are born.