Bertolt Brecht used the term "epic theatre" to describe his mode of drama-writing. This approach was designed to distinguish his work from traditional theatre, which Brecht felt focused too much on creating emotional engagement and empathy with the audience.
Epic theatre aimed to provoke critical thinking and social change by making the audience more conscious of the artificiality of the performance. Brecht used techniques such as breaking the fourth wall, using narrators, and employing a more fragmented narrative structure to prevent the audience from getting too emotionally involved, thereby encouraging them to think critically about the issues presented.
In contrast, the other options listed do not accurately describe Brecht's dramatic approach:
Musical theatre is a genre that incorporates music and dance but is not related to Brecht's method.
Proletarian theatre refers to theatre with themes centered around the working class, which Brecht's work often addressed, but this term does not specifically describe his mode of writing.
Kitchen-sink theatre is a term used for a style of drama that portrays the everyday lives of ordinary people, particularly in the UK during the late 1950s and early 1960s, and is not associated with Brecht's work.
So, "epic theatre" is the term that best describes Brecht's approach and distinguishes it from traditional theatre.