Which play is NOT authored by Bertolt Brecht?

The correct choice is "The Rivals," as it was written by Richard Brinsley Sheridan, not Bertolt Brecht. Brecht, a prominent 20th-century German playwright and poet, is known for his contributions to modern theatre, particularly his development of the concept of "epic theatre," which emphasizes the audience's critical engagement with the play rather than emotional involvement.

In contrast, "A Man's a Man" is a work by Brecht that explores themes of identity and transformation, while "The Life of Galileo" reflects his critical perspective on science and society, revealing his characteristic blend of philosophy and social critique. "Baal," another of Brecht's plays, showcases his innovative style and commitment to addressing social issues through theatre. Thus, while the other plays listed are significant works authored by Brecht, "The Rivals" stands apart as a classic of English theatre, leading to its identification as the play not associated with Brecht.